Trial Outcomes & Findings for A Study of Zika Vaccine mRNA-1893 in Adult Participants Living in Endemic and Non-Endemic Flavivirus Areas (NCT NCT04917861)

Last Updated: 2025-09-25

Results Overview

Solicited ARs (local and systemic) were collected in the electronic diary. Local ARs included: pain, erythema (redness), swelling/induration (hardness). Systemic ARs included: headache, fatigue, myalgia (muscle aches all over the body), arthralgia (aching in several joints), nausea/vomiting, body temperature (potentially fever), and chills. A summary of all serious adverse events (SAEs) and all nonserious adverse events (AEs) ("Other"), regardless of causality, is in Reported "Adverse Events" section.

Recruitment status

COMPLETED

Study phase

PHASE2

Target enrollment

808 participants

Primary outcome timeframe

Up to 7 days post-vaccination

Results posted on

2025-09-25

Participant Flow

A total of 808 participants were enrolled. One participant was randomized at two sites and received two injections. This participant was not presented under Per-Protocol Set but kept in Full Analysis Set, Safety Set, and Solicited Safety Set. This participant was discontinued from the study at one site upon the discovery of the duplicate participation and the incident was documented.

Participant milestones

Participant milestones
Measure	Placebo Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.
Main Study (196 Days) STARTED	203	201	203	201
Main Study (196 Days) Received First Injection	201	201	202	198
Main Study (196 Days) Received Second Injection	187	188	187	191
Main Study (196 Days) Randomized at Second Site	0	1	0	0
Main Study (196 Days) COMPLETED	173	166	176	178
Main Study (196 Days) NOT COMPLETED	30	35	27	23
Extension Period (Day 197 to Day 700) STARTED	113	109	104	116
Extension Period (Day 197 to Day 700) COMPLETED	97	96	89	93
Extension Period (Day 197 to Day 700) NOT COMPLETED	16	13	15	23

Reasons for withdrawal

Reasons for withdrawal
Measure	Placebo Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.
Main Study (196 Days) Adverse Event	0	1	0	0
Main Study (196 Days) Death	0	0	0	1
Main Study (196 Days) Lost to Follow-up	14	26	20	11
Main Study (196 Days) Physician Decision	0	0	0	1
Main Study (196 Days) Pregnancy	1	1	0	0
Main Study (196 Days) Withdrawal by Subject	14	7	6	8
Main Study (196 Days) Other Than Specified	1	0	1	2
Extension Period (Day 197 to Day 700) Lost to Follow-up	8	3	5	11
Extension Period (Day 197 to Day 700) Pregnancy	1	0	1	1
Extension Period (Day 197 to Day 700) Protocol Violation	0	1	0	0
Extension Period (Day 197 to Day 700) Withdrawal by Subject	6	8	8	10
Extension Period (Day 197 to Day 700) Other Than Specified	1	0	1	1
Extension Period (Day 197 to Day 700) Death	0	1	0	0

Baseline Characteristics

A Study of Zika Vaccine mRNA-1893 in Adult Participants Living in Endemic and Non-Endemic Flavivirus Areas

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Placebo n=201 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=201 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=202 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) ( n=198 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Total n=802 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants
Age, Categorical Between 18 and 65 years	201 Participants n=5 Participants	201 Participants n=7 Participants	202 Participants n=5 Participants	198 Participants n=4 Participants	802 Participants n=21 Participants
Age, Categorical >=65 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants
Sex: Female, Male Female	111 Participants n=5 Participants	119 Participants n=7 Participants	119 Participants n=5 Participants	114 Participants n=4 Participants	463 Participants n=21 Participants
Sex: Female, Male Male	90 Participants n=5 Participants	82 Participants n=7 Participants	83 Participants n=5 Participants	84 Participants n=4 Participants	339 Participants n=21 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	106 Participants n=5 Participants	106 Participants n=7 Participants	110 Participants n=5 Participants	107 Participants n=4 Participants	429 Participants n=21 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	94 Participants n=5 Participants	94 Participants n=7 Participants	91 Participants n=5 Participants	90 Participants n=4 Participants	369 Participants n=21 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	1 Participants n=5 Participants	1 Participants n=7 Participants	1 Participants n=5 Participants	1 Participants n=4 Participants	4 Participants n=21 Participants
Race/Ethnicity, Customized Race · White	167 Participants n=5 Participants	167 Participants n=7 Participants	174 Participants n=5 Participants	172 Participants n=4 Participants	680 Participants n=21 Participants
Race/Ethnicity, Customized Race · Black or African American	28 Participants n=5 Participants	25 Participants n=7 Participants	22 Participants n=5 Participants	21 Participants n=4 Participants	96 Participants n=21 Participants
Race/Ethnicity, Customized Race · Asian	0 Participants n=5 Participants	2 Participants n=7 Participants	1 Participants n=5 Participants	2 Participants n=4 Participants	5 Participants n=21 Participants
Race/Ethnicity, Customized Race · American Indian or Alaska Native	0 Participants n=5 Participants	3 Participants n=7 Participants	2 Participants n=5 Participants	2 Participants n=4 Participants	7 Participants n=21 Participants
Race/Ethnicity, Customized Race · Native Hawaiian or other Pacific Islander	1 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	1 Participants n=21 Participants
Race/Ethnicity, Customized Race · Multiracial	3 Participants n=5 Participants	1 Participants n=7 Participants	2 Participants n=5 Participants	1 Participants n=4 Participants	7 Participants n=21 Participants
Race/Ethnicity, Customized Race · Other	1 Participants n=5 Participants	3 Participants n=7 Participants	1 Participants n=5 Participants	0 Participants n=4 Participants	5 Participants n=21 Participants
Race/Ethnicity, Customized Race · Not reported	1 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	1 Participants n=21 Participants
Seroresponse Flavivirus Seronegative Participants	96 Participants n=5 Participants	92 Participants n=7 Participants	105 Participants n=5 Participants	111 Participants n=4 Participants	404 Participants n=21 Participants
Seroresponse Flavivirus Seropositive Participants	102 Participants n=5 Participants	103 Participants n=7 Participants	94 Participants n=5 Participants	82 Participants n=4 Participants	381 Participants n=21 Participants
Seroresponse Missing	3 Participants n=5 Participants	6 Participants n=7 Participants	3 Participants n=5 Participants	5 Participants n=4 Participants	17 Participants n=21 Participants

PRIMARY outcome

Timeframe: Up to 7 days post-vaccination

Population: The Solicited Safety Set included all participants who were randomized, received any study injection, and contributed with any solicited AR data. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Solicited Safety Set for collection and reporting data.

Outcome measures

Outcome measures
Measure	Placebo n=200 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=201 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=201 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=198 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Number of Participants With Solicited Local and Systemic Reactogenicity Adverse Reactions (ARs)	86 Participants	164 Participants	183 Participants	163 Participants	—	—	—	—

PRIMARY outcome

Timeframe: Up to 28 days post-vaccination

Population: The Safety Set included all participants who were randomized and received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Safety Set for collection and reporting data.

An unsolicited AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. Unsolicited AEs were AEs that were not included in the protocol-defined solicited ARs. A treatment-emergent adverse event (TEAE) was defined as any AE not present before exposure to vaccine or any AE already present that worsened in intensity or frequency after exposure. A summary of all SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	Placebo n=201 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=202 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=202 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=198 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Number of Participants With Unsolicited Adverse Events (AEs)	39 Participants	47 Participants	52 Participants	45 Participants	—	—	—	—

PRIMARY outcome

Timeframe: Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period

An SAE was defined as any AE that resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, was a congenital anomaly/birth defect, or was an important medical event. An AESI was an AE (serious or nonserious) of scientific and medical concern specific to the Sponsor's product or program, for which ongoing monitoring and immediate notification by the Investigator to the Sponsor were required. A summary of all SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	Placebo n=201 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=202 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=202 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=198 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo n=113 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) n=109 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) n=104 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) n=116 Participants Participants were followed up for up to Day 700 in the extension period.
Number of Participants With Serious Adverse Events (SAEs), AEs of Special Interest (AESIs) SAEs	5 Participants	2 Participants	4 Participants	7 Participants	5 Participants	4 Participants	5 Participants	7 Participants
Number of Participants With Serious Adverse Events (SAEs), AEs of Special Interest (AESIs) AESIs	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants

PRIMARY outcome

Timeframe: Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period

An MAAE was an AE that led to an unscheduled visit to a healthcare practitioner. Note that the generation of the tables for the MAAE data for the Main Study occurred after the start of the Extension Period. Therefore, some of the MAAE data for this outcome measure may appear both in the Main Study and the Extension Period. A summary of all SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	Placebo n=201 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=202 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=202 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=198 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo n=113 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) n=109 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) n=104 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) n=116 Participants Participants were followed up for up to Day 700 in the extension period.
Number of Participants With Medically Attended AEs (MAAEs)	62 Participants	50 Participants	62 Participants	63 Participants	29 Participants	24 Participants	30 Participants	31 Participants

PRIMARY outcome

Timeframe: Day 57

Population: The Per-Protocol Set for Antibody-Mediated Immunogenicity (PPAMI) included all participants who received any study injection, who did not have major protocol deviations that impacted AMI response, and who complied with the injection schedule and the timing of immunogenicity blood sampling to have post-injection results available for at least 1 assay component of AMI at the corresponding visit. Here, 'Number analyzed' = participants evaluable for specified categories.

Antibody values reported as below the lower limit of quantification (LLOQ) were replaced by 0.5 \* LLOQ. Values that were greater than the upper limit of quantification (ULOQ) were converted to the ULOQ. LLOQ=91; ULOQ=24814. 95% confidence interval (CI) was calculated based on the t-distribution of the log-transformed values, then back transformed to the original scale for presentation.

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Geometric Mean Titer (GMT) of Zika Virus (ZIKV)-Specific Neutralizing Antibodies (nAbs) at Day 57, as Measured by 50% Plaque Reduction Neutralization Test (PRNT50) All Participants	61.06 titer Interval 54.07 to 68.96	427.53 titer Interval 343.28 to 532.45	434.92 titer Interval 343.63 to 550.46	163.28 titer Interval 122.68 to 217.3	—	—	—	—
Geometric Mean Titer (GMT) of Zika Virus (ZIKV)-Specific Neutralizing Antibodies (nAbs) at Day 57, as Measured by 50% Plaque Reduction Neutralization Test (PRNT50) Flavivirus-seronegative Participants	45.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	327.95 titer Interval 246.98 to 435.47	363.03 titer Interval 277.84 to 474.35	68.96 titer Interval 55.94 to 85.02	—	—	—	—
Geometric Mean Titer (GMT) of Zika Virus (ZIKV)-Specific Neutralizing Antibodies (nAbs) at Day 57, as Measured by 50% Plaque Reduction Neutralization Test (PRNT50) Flavivirus-seropositive Participants	79.46 titer Interval 63.92 to 98.78	539.17 titer Interval 385.76 to 753.59	502.11 titer Interval 337.76 to 746.45	558.49 titer Interval 336.21 to 927.73	—	—	—	—

PRIMARY outcome

Timeframe: Day 57

Population: The PPAMI included all participants who received any study injection, who did not have major protocol deviations that impacted AMI response, and who complied with the injection schedule and the timing of immunogenicity blood sampling to have post-injection results available for at least 1 assay component of AMI at the corresponding visit. Here, 'Number analyzed' = participants evaluable for specified categories.

Antibody values reported as below the LLOQ were replaced by 0.5 \* LLOQ. Values that were greater than the ULOQ were converted to the ULOQ. LLOQ=91; ULOQ=24814. 95% CI was calculated based on the t-distribution of the log-transformed values, then back transformed to the original scale for presentation.

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
GMT of ZIKV-specific nAbs at Day 57, as Measured by 80% Plaque Reduction Neutralization Test (PRNT80) All Participants	20.80 titer Interval 18.6 to 23.26	110.52 titer Interval 88.59 to 137.88	111.21 titer Interval 88.04 to 140.48	48.36 titer Interval 36.56 to 63.97	—	—	—	—
GMT of ZIKV-specific nAbs at Day 57, as Measured by 80% Plaque Reduction Neutralization Test (PRNT80) Flavivirus-seronegative Participants	16.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	69.64 titer Interval 54.81 to 88.48	87.45 titer Interval 70.01 to 109.24	19.89 titer Interval 17.05 to 23.21	—	—	—	—
GMT of ZIKV-specific nAbs at Day 57, as Measured by 80% Plaque Reduction Neutralization Test (PRNT80) Flavivirus-seropositive Participants	25.60 titer Interval 20.88 to 31.38	166.23 titer Interval 117.69 to 234.8	139.57 titer Interval 91.83 to 212.13	174.18 titer Interval 104.33 to 290.79	—	—	—	—

PRIMARY outcome

Timeframe: Day 57

Seroconversion was defined as an increase in ZIKV-specific nAb titer from below the LLOQ to a titer equal to or above LLOQ, or an increase of at least 4-fold in ZIKV-specific nAb titer in participants with pre-existing nAb titers. LLOQ=91; ULOQ=24814.

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Participants With Seroconversion at Day 57, as Measured by PRNT50 All Participants	4.3 percentage of participants Interval 1.74 to 8.65	81.0 percentage of participants Interval 74.1 to 86.7	82.1 percentage of participants Interval 75.31 to 87.67	39.9 percentage of participants Interval 32.3 to 47.83	—	—	—	—
Percentage of Participants With Seroconversion at Day 57, as Measured by PRNT50 Flavivirus-seronegative Participants	0 percentage of participants Interval 0.0 to 4.74	86.1 percentage of participants Interval 75.94 to 93.13	87.7 percentage of participants Interval 78.47 to 93.92	20.4 percentage of participants Interval 12.77 to 30.05	—	—	—	—
Percentage of Participants With Seroconversion at Day 57, as Measured by PRNT50 Flavivirus-seropositive Participants	8.1 percentage of participants Interval 3.34 to 16.05	75.9 percentage of participants Interval 65.5 to 84.4	75.9 percentage of participants Interval 65.02 to 84.86	65.7 percentage of participants Interval 53.06 to 76.85	—	—	—	—

PRIMARY outcome

Timeframe: Day 57

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Participants With Seroconversion at Day 57, as Measured by PRNT80 All Participants	1.2 percentage of participants Interval 0.15 to 4.36	76.7 percentage of participants Interval 69.43 to 82.94	76.5 percentage of participants Interval 69.25 to 82.83	32.5 percentage of participants Interval 25.4 to 40.28	—	—	—	—
Percentage of Participants With Seroconversion at Day 57, as Measured by PRNT80 Flavivirus-seronegative Participants	0 percentage of participants Interval 0.0 to 4.74	77.8 percentage of participants Interval 66.44 to 86.73	82.7 percentage of participants Interval 72.7 to 90.22	9.7 percentage of participants Interval 4.52 to 17.58	—	—	—	—
Percentage of Participants With Seroconversion at Day 57, as Measured by PRNT80 Flavivirus-seropositive Participants	2.3 percentage of participants Interval 0.28 to 8.15	74.7 percentage of participants Interval 64.25 to 83.42	69.6 percentage of participants Interval 58.25 to 79.47	65.7 percentage of participants Interval 53.06 to 76.85	—	—	—	—

SECONDARY outcome

Timeframe: Days 1, 8, 29, and 36

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 1: All Participants by PRNT50	60.64 titer Interval 53.33 to 68.95	61.21 titer Interval 53.93 to 69.46	54.57 titer Interval 49.53 to 60.13	59.41 titer Interval 52.45 to 67.29	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: All Participants by PRNT50	62.15 titer Interval 54.37 to 71.04	116.92 titer Interval 90.06 to 151.81	105.78 titer Interval 80.71 to 138.64	57.98 titer Interval 51.17 to 65.69	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: All Participants by PRNT50	66.66 titer Interval 57.15 to 77.76	151.34 titer Interval 115.71 to 197.94	140.50 titer Interval 107.24 to 184.08	59.59 titer Interval 52.1 to 68.15	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: All Participants by PRNT50	58.51 titer Interval 52.16 to 65.63	493.59 titer Interval 382.88 to 636.3	412.24 titer Interval 316.08 to 537.65	118.04 titer Interval 89.84 to 155.09	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 1: Flavivirus-negative Participants by PRNT50	45.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	50.76 titer Interval 43.31 to 59.49	45.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	48.58 titer Interval 44.97 to 52.48	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-negative Participants by PRNT50	45.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	50.24 titer Interval 43.73 to 57.71	48.05 titer Interval 44.03 to 52.43	50.30 titer Interval 45.07 to 56.15	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-negative Participants by PRNT50	46.45 titer Interval 44.58 to 48.39	57.81 titer Interval 48.16 to 69.4	67.45 titer Interval 56.47 to 80.56	48.85 titer Interval 45.24 to 52.75	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-negative Participants by PRNT50	45.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	478.42 titer Interval 346.32 to 660.91	344.02 titer Interval 249.51 to 474.33	56.46 titer Interval 46.29 to 68.86	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 1: Flavivirus-positive Participants by PRNT50	78.42 titer Interval 62.17 to 98.91	72.45 titer Interval 59.72 to 87.88	66.06 titer Interval 54.52 to 80.03	79.50 titer Interval 60.53 to 104.4	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT50	81.87 titer Interval 64.46 to 103.98	245.67 titer Interval 161.42 to 373.91	245.31 titer Interval 150.29 to 400.42	71.60 titer Interval 55.17 to 92.92	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT50	92.15 titer Interval 70.05 to 121.22	350.77 titer Interval 234.46 to 524.78	295.81 titer Interval 184.73 to 473.71	79.46 titer Interval 58.87 to 107.25	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT50	73.48 titer Interval 59.61 to 90.57	507.03 titer Interval 340.84 to 754.26	487.78 titer Interval 315.43 to 754.3	339.16 titer Interval 203.88 to 564.2	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 1: All Participants by PRNT80	21.06 titer Interval 18.82 to 23.58	21.23 titer Interval 19.13 to 23.56	18.94 titer Interval 17.56 to 20.42	19.60 titer Interval 17.84 to 21.54	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: All Participants by PRNT80	20.50 titer Interval 18.46 to 22.77	40.88 titer Interval 31.55 to 52.97	37.44 titer Interval 28.52 to 49.16	20.10 titer Interval 18.01 to 22.42	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: All Participants by PRNT80	21.07 titer Interval 18.94 to 23.44	49.95 titer Interval 38.14 to 65.42	43.46 titer Interval 33.06 to 57.13	19.72 titer Interval 17.83 to 21.82	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: All Participants by PRNT80	20.40 titer Interval 18.42 to 22.59	124.30 titer Interval 97.25 to 158.87	121.27 titer Interval 93.24 to 157.71	39.69 titer Interval 30.34 to 51.92	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 1: Flavivirus-negative Participants by PRNT80	16.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	18.06 titer Interval 15.91 to 20.49	16.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	17.63 titer Interval 16.28 to 19.1	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-negative Participants by PRNT80	16.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	18.43 titer Interval 15.78 to 21.52	17.24 titer Interval 15.8 to 18.81	17.58 titer Interval 16.22 to 19.05	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-negative Participants by PRNT80	16.95 titer Interval 16.07 to 17.88	18.75 titer Interval 16.15 to 21.75	19.06 titer Interval 16.73 to 21.72	17.64 titer Interval 16.25 to 19.15	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-negative Participants by PRNT80	16.50 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	95.88 titer Interval 71.94 to 127.78	89.62 titer Interval 66.16 to 121.4	19.02 titer Interval 16.09 to 22.48	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 1: Flavivirus-positive Participants by PRNT80	26.21 titer Interval 21.36 to 32.16	24.56 titer Interval 20.91 to 28.85	21.89 titer Interval 18.84 to 25.42	22.89 titer Interval 18.78 to 27.89	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT80	24.84 titer Interval 20.54 to 30.04	82.41 titer Interval 54.22 to 125.26	85.57 titer Interval 52.06 to 140.65	24.49 titer Interval 19.27 to 31.12	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT80	25.61 titer Interval 21.21 to 30.93	116.95 titer Interval 77.36 to 176.79	99.92 titer Interval 61.83 to 161.47	23.21 titer Interval 18.71 to 28.79	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT80	24.73 titer Interval 20.52 to 29.81	156.24 titer Interval 105.6 to 231.16	161.96 titer Interval 104.84 to 250.22	113.38 titer Interval 67.59 to 190.2	—	—	—	—

SECONDARY outcome

Timeframe: Days 1, 8, 29, 36, and 57

Antibody values reported as below the LLOQ were replaced by 0.5 \* LLOQ. Values that were greater than the ULOQ were converted to the ULOQ. LLOQ=28; ULOQ=11589. 95% CI was calculated based on the t-distribution of the log-transformed values, then back transformed to the original scale for presentation.

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 1: All Participants	30.54 titer Interval 24.08 to 38.73	32.98 titer Interval 26.18 to 41.55	25.31 titer Interval 20.43 to 31.36	27.94 titer Interval 22.45 to 34.78	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 8: All Participants	27.99 titer Interval 22.52 to 34.8	76.17 titer Interval 52.37 to 110.79	80.70 titer Interval 55.4 to 117.55	24.68 titer Interval 20.43 to 29.8	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 29: All Participants	32.05 titer Interval 25.2 to 40.75	489.20 titer Interval 365.8 to 654.24	544.38 titer Interval 416.59 to 711.36	28.61 titer Interval 22.85 to 35.83	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 36: All Participants	27.74 titer Interval 22.42 to 34.32	1318.97 titer Interval 1068.49 to 1628.15	1380.12 titer Interval 1109.4 to 1716.91	81.79 titer Interval 56.62 to 118.15	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 57: All Participants	31.60 titer Interval 24.81 to 40.24	2261.02 titer Interval 1903.39 to 2685.84	2270.12 titer Interval 1907.12 to 2702.22	643.02 titer Interval 491.83 to 840.67	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 1: Flavivirus-negative Participants	14.00 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	16.25 titer Interval 13.69 to 19.3	14.00 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	15.99 titer Interval 13.66 to 18.72	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 8: Flavivirus-negative Participants	14.00 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	17.73 titer Interval 13.79 to 22.8	20.22 titer Interval 16.32 to 25.04	15.66 titer Interval 13.76 to 17.82	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 29: Flavivirus-negative Participants	14.00 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	200.15 titer Interval 148.92 to 268.99	285.93 titer Interval 211.77 to 386.07	16.92 titer Interval 13.99 to 20.47	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 36: Flavivirus-negative Participants	14.00 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	1428.20 titer Interval 1110.81 to 1836.29	1237.86 titer Interval 923.46 to 1659.31	23.16 titer Interval 17.78 to 30.17	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 57: Flavivirus-negative Participants	14.00 titer Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	2291.24 titer Interval 1821.46 to 2882.2	2235.55 titer Interval 1826.02 to 2736.92	280.91 titer Interval 211.58 to 372.97	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 1: Flavivirus-positive Participants	61.39 titer Interval 41.21 to 91.45	61.63 titer Interval 42.84 to 88.66	47.15 titer Interval 31.65 to 70.26	62.55 titer Interval 41.06 to 95.28	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 8: Flavivirus-positive Participants	51.65 titer Interval 35.8 to 74.5	275.14 titer Interval 159.62 to 474.24	348.73 titer Interval 193.37 to 628.91	47.58 titer Interval 32.7 to 69.24	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 29: Flavivirus-positive Participants	67.27 titer Interval 45.25 to 99.98	1040.81 titer Interval 680.49 to 1591.92	1067.67 titer Interval 711.8 to 1601.47	61.27 titer Interval 40.18 to 93.42	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 36: Flavivirus-positive Participants	51.54 titer Interval 35.96 to 73.87	1260.49 titer Interval 898.36 to 1768.61	1504.49 titer Interval 1076.56 to 2102.53	493.88 titer Interval 273.73 to 891.11	—	—	—	—
GMT of ZIKV-Specific nAbs at Days 1, 8, 29, 36, and 57, as Measured by Microneutralization (MN) Day 57: Flavivirus-positive Participants	65.50 titer Interval 43.82 to 97.91	2246.56 titer Interval 1727.41 to 2921.74	2253.47 titer Interval 1681.38 to 3020.2	2002.83 titer Interval 1367.92 to 2932.43	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, 36, and 57

Antibody values reported as below the LLOQ were replaced by 0.5 \* LLOQ. Values that were greater than the ULOQ were converted to the ULOQ. LLOQ=91; ULOQ=248. 95% CI was calculated based on the t-distribution of the difference in the log-transformed values, then back transformed to the original scale for presentation.

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT50	1.18 ratio Interval 0.96 to 1.43	4.84 ratio Interval 3.42 to 6.85	4.48 ratio Interval 3.03 to 6.61	1.00 ratio Interval 0.83 to 1.2	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT50	0.93 ratio Interval 0.81 to 1.08	7.00 ratio Interval 4.85 to 10.09	7.38 ratio Interval 5.04 to 10.81	4.27 ratio Interval 2.74 to 6.64	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 57: Flavivirus-positive Participants by PRNT50	1.01 ratio Interval 0.87 to 1.19	7.44 ratio Interval 5.4 to 10.25	7.60 ratio Interval 5.42 to 10.66	7.03 ratio Interval 4.61 to 10.7	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 8: All Participants by PRNT80	0.97 ratio Interval 0.94 to 1.01	1.93 ratio Interval 1.57 to 2.36	1.98 ratio Interval 1.57 to 2.49	1.03 ratio Interval 0.98 to 1.09	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 29: All Participants by PRNT80	1.00 ratio Interval 0.96 to 1.04	2.35 ratio Interval 1.88 to 2.94	2.29 ratio Interval 1.82 to 2.9	1.01 ratio Interval 0.99 to 1.03	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 36: All Participants by PRNT80	0.97 ratio Interval 0.92 to 1.01	5.85 ratio Interval 4.72 to 7.27	6.40 ratio Interval 5.06 to 8.09	2.02 ratio Interval 1.63 to 2.52	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 57: All Participants by PRNT80	0.99 ratio Interval 0.94 to 1.04	5.21 ratio Interval 4.28 to 6.33	5.87 ratio Interval 4.79 to 7.21	2.47 ratio Interval 1.94 to 3.13	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 57: All Participants by PRNT50	1.01 ratio Interval 0.93 to 1.09	6.98 ratio Interval 5.68 to 8.59	7.97 ratio Interval 6.45 to 9.85	2.75 ratio Interval 2.18 to 3.46	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-negative Participants by PRNT50	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	0.99 ratio Interval 0.95 to 1.03	1.06 ratio Interval 0.97 to 1.15	1.04 ratio Interval 0.95 to 1.13	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-negative Participants by PRNT50	1.02 ratio Interval 0.98 to 1.06	1.14 ratio Interval 1.02 to 1.27	1.48 ratio Interval 1.24 to 1.77	1.01 ratio Interval 0.98 to 1.03	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-negative Participants by PRNT50	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	9.43 ratio Interval 6.7 to 13.26	7.56 ratio Interval 5.48 to 10.42	1.16 ratio Interval 1.0 to 1.34	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 57: Flavivirus-negative Participants by PRNT50	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	6.46 ratio Interval 4.92 to 8.48	7.98 ratio Interval 6.11 to 10.43	1.42 ratio Interval 1.2 to 1.68	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT50	1.04 ratio Interval 0.9 to 1.21	3.39 ratio Interval 2.37 to 4.84	3.70 ratio Interval 2.44 to 5.61	0.90 ratio Interval 0.69 to 1.19	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 8: All Participants by PRNT50	1.02 ratio Interval 0.94 to 1.11	1.91 ratio Interval 1.55 to 2.36	1.94 ratio Interval 1.54 to 2.43	0.98 ratio Interval 0.87 to 1.1	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 29: All Participants by PRNT50	1.10 ratio Interval 0.99 to 1.22	2.47 ratio Interval 1.98 to 3.08	2.57 ratio Interval 2.05 to 3.23	1.00 ratio Interval 0.93 to 1.08	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 36: All Participants by PRNT50	0.96 ratio Interval 0.89 to 1.04	8.06 ratio Interval 6.3 to 10.32	7.55 ratio Interval 5.91 to 9.63	1.98 ratio Interval 1.59 to 2.48	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-negative Participants by PRNT80	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	1.02 ratio Interval 0.99 to 1.05	1.04 ratio Interval 0.96 to 1.14	1.00 ratio Interval 0.98 to 1.01	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-negative Participants by PRNT80	1.03 ratio Interval 0.97 to 1.08	1.04 ratio Interval 0.97 to 1.11	1.16 ratio Interval 1.01 to 1.32	1.00 ratio Interval 0.99 to 1.01	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-negative Participants by PRNT80	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	5.31 ratio Interval 4.02 to 7.02	5.43 ratio Interval 4.01 to 7.36	1.08 ratio Interval 0.99 to 1.18	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 57: Flavivirus-negative Participants by PRNT80	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	3.86 ratio Interval 3.03 to 4.91	5.30 ratio Interval 4.24 to 6.62	1.13 ratio Interval 1.04 to 1.23	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT80	0.95 ratio Interval 0.89 to 1.01	3.36 ratio Interval 2.38 to 4.74	3.90 ratio Interval 2.55 to 5.94	1.09 ratio Interval 0.95 to 1.24	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT80	0.98 ratio Interval 0.93 to 1.03	4.76 ratio Interval 3.34 to 6.79	4.57 ratio Interval 3.05 to 6.84	1.01 ratio Interval 0.96 to 1.07	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT80	0.94 ratio Interval 0.86 to 1.03	6.36 ratio Interval 4.55 to 8.9	7.40 ratio Interval 5.12 to 10.69	4.95 ratio Interval 3.21 to 7.65	—	—	—	—
Geometric Mean Fold Rise (GMFR) of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by PRNT50 and PRNT80 Day 57: Flavivirus-positive Participants by PRNT80	0.98 ratio Interval 0.89 to 1.07	6.77 ratio Interval 5.01 to 9.15	6.38 ratio Interval 4.48 to 9.08	7.61 ratio Interval 4.84 to 11.96	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, 36, and 57

Antibody values reported as below the LLOQ were replaced by 0.5 \* LLOQ. Values that were greater than the ULOQ were converted to the ULOQ. LLOQ=28; ULOQ=11589. 95% CI was calculated based on the t-distribution of the difference in the log-transformed values, then back transformed to the original scale for presentation.

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 8: All Participants	0.91 ratio Interval 0.85 to 0.97	2.31 ratio Interval 1.87 to 2.85	3.19 ratio Interval 2.5 to 4.06	0.88 ratio Interval 0.82 to 0.95	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 29: All Participants	1.05 ratio Interval 0.97 to 1.13	14.75 ratio Interval 12.03 to 18.09	21.51 ratio Interval 17.65 to 26.21	1.02 ratio Interval 0.96 to 1.09	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 36: All Participants	0.90 ratio Interval 0.84 to 0.97	39.99 ratio Interval 31.83 to 50.25	54.33 ratio Interval 43.9 to 67.23	2.91 ratio Interval 2.34 to 3.64	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 57: All Participants	1.03 ratio Interval 0.96 to 1.12	68.55 ratio Interval 54.98 to 85.48	89.69 ratio Interval 72.82 to 110.47	23.01 ratio Interval 18.89 to 28.03	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 8: Flavivirus-negative Participants	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	1.09 ratio Interval 0.95 to 1.25	1.44 ratio Interval 1.17 to 1.79	0.98 ratio Interval 0.94 to 1.02	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 29: Flavivirus-negative Participants	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	12.29 ratio Interval 9.46 to 15.97	20.42 ratio Interval 15.13 to 27.58	1.06 ratio Interval 0.96 to 1.16	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 36: Flavivirus-negative Participants	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	87.88 ratio Interval 67.32 to 114.73	88.42 ratio Interval 65.96 to 118.52	1.45 ratio Interval 1.22 to 1.72	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 57: Flavivirus-negative Participants	1.00 ratio Due to not enough variability in the values, the CI (upper and lower limit) could not be calculated.	140.99 ratio Interval 108.71 to 182.85	159.68 ratio Interval 130.43 to 195.49	17.57 ratio Interval 13.53 to 22.8	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 8: Flavivirus-positive Participants	0.84 ratio Interval 0.75 to 0.95	4.46 ratio Interval 3.24 to 6.15	7.40 ratio Interval 5.12 to 10.68	0.76 ratio Interval 0.65 to 0.9	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 29: Flavivirus-positive Participants	1.10 ratio Interval 0.94 to 1.27	16.89 ratio Interval 12.39 to 23.02	22.64 ratio Interval 17.39 to 29.48	0.98 ratio Interval 0.89 to 1.07	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 36: Flavivirus-positive Participants	0.83 ratio Interval 0.73 to 0.94	20.45 ratio Interval 15.07 to 27.76	31.91 ratio Interval 24.26 to 41.95	7.90 ratio Interval 5.45 to 11.43	—	—	—	—
GMFR of ZIKV-Specific nAbs at Days 8, 29, 36, and 57, as Measured by MN Day 57: Flavivirus-positive Participants	1.07 ratio Interval 0.92 to 1.24	36.45 ratio Interval 27.11 to 49.02	47.79 ratio Interval 34.69 to 65.84	32.02 ratio Interval 23.77 to 43.13	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, and 36

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: All Participants by PRNT80	0 percentage of participants Interval 0.0 to 2.25	19.6 percentage of participants Interval 13.83 to 26.57	19.3 percentage of participants Interval 13.47 to 26.2	1.2 percentage of participants Interval 0.15 to 4.39	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: All Participants by PRNT50	3.1 percentage of participants Interval 1.01 to 7.06	20.9 percentage of participants Interval 14.9 to 27.91	21.1 percentage of participants Interval 15.09 to 28.24	4.3 percentage of participants Interval 1.75 to 8.7	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: All Participants by PRNT50	6.7 percentage of participants Interval 3.42 to 11.75	33.3 percentage of participants Interval 26.13 to 41.16	38.3 percentage of participants Interval 30.76 to 46.22	3.7 percentage of participants Interval 1.36 to 7.84	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: All Participants by PRNT50	1.9 percentage of participants Interval 0.38 to 5.32	76.1 percentage of participants Interval 68.78 to 82.4	75.2 percentage of participants Interval 67.74 to 81.62	21.0 percentage of participants Interval 14.99 to 28.07	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-negative Participants by PRNT50	0 percentage of participants Interval 0.0 to 4.8	0 percentage of participants Interval 0.0 to 4.99	2.5 percentage of participants Interval 0.3 to 8.64	1.1 percentage of participants Interval 0.03 to 5.85	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-negative Participants by PRNT50	1.3 percentage of participants Interval 0.03 to 7.11	8.5 percentage of participants Interval 3.16 to 17.49	25.9 percentage of participants Interval 16.82 to 36.86	1.1 percentage of participants Interval 0.03 to 5.85	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-negative Participants by PRNT50	0 percentage of participants Interval 0.0 to 4.74	86.1 percentage of participants Interval 75.94 to 93.13	78.8 percentage of participants Interval 68.17 to 87.11	4.3 percentage of participants Interval 1.2 to 10.76	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT50	5.8 percentage of participants Interval 1.91 to 13.05	39.1 percentage of participants Interval 28.79 to 50.13	41.0 percentage of participants Interval 30.01 to 52.75	9.1 percentage of participants Interval 3.41 to 18.74	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT50	11.6 percentage of participants Interval 5.72 to 20.35	55.2 percentage of participants Interval 44.13 to 65.85	50.6 percentage of participants Interval 39.14 to 62.08	7.5 percentage of participants Interval 2.47 to 16.56	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT50	3.5 percentage of participants Interval 0.73 to 9.97	66.7 percentage of participants Interval 55.75 to 76.42	70.9 percentage of participants Interval 59.58 to 80.57	44.8 percentage of participants Interval 32.6 to 57.42	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: All Participants by PRNT80	1.2 percentage of participants Interval 0.15 to 4.36	31.5 percentage of participants Interval 24.42 to 39.23	29.0 percentage of participants Interval 22.16 to 36.65	0 percentage of participants Interval 0.0 to 2.24	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: All Participants by PRNT80	1.2 percentage of participants Interval 0.15 to 4.39	72.4 percentage of participants Interval 64.86 to 79.1	72.0 percentage of participants Interval 64.44 to 78.83	22.8 percentage of participants Interval 16.62 to 30.08	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-negative Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.8	0 percentage of participants Interval 0.0 to 4.99	1.2 percentage of participants Interval 0.03 to 6.69	0 percentage of participants Interval 0.0 to 3.89	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-negative Participants by PRNT80	1.3 percentage of participants Interval 0.03 to 7.11	2.8 percentage of participants Interval 0.34 to 9.81	7.4 percentage of participants Interval 2.77 to 15.43	0 percentage of participants Interval 0.0 to 3.89	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-negative Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.74	75.0 percentage of participants Interval 63.4 to 84.46	71.3 percentage of participants Interval 60.05 to 80.82	3.3 percentage of participants Interval 0.68 to 9.23	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.2	36.8 percentage of participants Interval 26.69 to 47.8	38.5 percentage of participants Interval 27.66 to 50.17	3.0 percentage of participants Interval 0.37 to 10.52	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT80	1.2 percentage of participants Interval 0.03 to 6.31	56.3 percentage of participants Interval 45.26 to 66.94	50.6 percentage of participants Interval 39.14 to 62.08	0 percentage of participants Interval 0.0 to 5.36	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT80	2.4 percentage of participants Interval 0.29 to 8.24	69.0 percentage of participants Interval 58.14 to 78.45	72.2 percentage of participants Interval 60.93 to 81.65	50.7 percentage of participants Interval 38.24 to 63.18	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, 36, and 57

Outcome measures

Outcome measures
Measure	Placebo n=163 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=163 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=162 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=163 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 57: Flavivirus-negative Participants	0 percentage of participants Interval 0.0 to 4.74	98.6 percentage of participants Interval 92.5 to 99.96	100.0 percentage of participants Interval 95.55 to 100.0	94.6 percentage of participants Interval 87.9 to 98.23	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 8: All Participants	1.2 percentage of participants Interval 0.15 to 4.39	35.0 percentage of participants Interval 27.68 to 42.82	41.4 percentage of participants Interval 33.69 to 49.35	1.2 percentage of participants Interval 0.15 to 4.36	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 29: All Participants	1.8 percentage of participants Interval 0.38 to 5.28	93.2 percentage of participants Interval 88.18 to 96.56	95.7 percentage of participants Interval 91.3 to 98.25	1.8 percentage of participants Interval 0.38 to 5.28	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 36: All Participants	1.2 percentage of participants Interval 0.15 to 4.39	92.6 percentage of participants Interval 87.49 to 96.14	96.3 percentage of participants Interval 92.07 to 98.62	40.7 percentage of participants Interval 33.1 to 48.73	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 57: All Participants	1.8 percentage of participants Interval 0.38 to 5.28	95.7 percentage of participants Interval 91.35 to 98.26	97.5 percentage of participants Interval 93.8 to 99.32	95.7 percentage of participants Interval 91.35 to 98.26	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 8: Flavivirus-negative Participants	0 percentage of participants Interval 0.0 to 4.8	8.3 percentage of participants Interval 3.12 to 17.26	16.0 percentage of participants Interval 8.83 to 25.88	0 percentage of participants Interval 0.0 to 3.89	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 29: Flavivirus-negative Participants	0 percentage of participants Interval 0.0 to 4.74	97.2 percentage of participants Interval 90.19 to 99.66	95.1 percentage of participants Interval 87.84 to 98.64	1.1 percentage of participants Interval 0.03 to 5.85	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 36: Flavivirus-negative Participants	0 percentage of participants Interval 0.0 to 4.74	98.6 percentage of participants Interval 92.5 to 99.96	97.5 percentage of participants Interval 91.26 to 99.7	18.5 percentage of participants Interval 11.15 to 27.93	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 8: Flavivirus-positive Participants	2.3 percentage of participants Interval 0.28 to 8.15	58.6 percentage of participants Interval 47.55 to 69.08	68.4 percentage of participants Interval 56.92 to 78.37	3.0 percentage of participants Interval 0.36 to 10.37	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 29: Flavivirus-positive Participants	3.5 percentage of participants Interval 0.73 to 9.86	89.7 percentage of participants Interval 81.27 to 95.16	96.2 percentage of participants Interval 89.3 to 99.21	3.0 percentage of participants Interval 0.36 to 10.37	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 36: Flavivirus-positive Participants	2.4 percentage of participants Interval 0.29 to 8.24	87.4 percentage of participants Interval 78.5 to 93.52	94.9 percentage of participants Interval 87.54 to 98.6	71.6 percentage of participants Interval 59.31 to 81.99	—	—	—	—
Percentage of Participants With Seroconversion at Days 8, 29, 36, and 57, as Measured by MN Day 57: Flavivirus-positive Participants	3.5 percentage of participants Interval 0.73 to 9.86	93.1 percentage of participants Interval 85.59 to 97.43	94.9 percentage of participants Interval 87.54 to 98.6	97.0 percentage of participants Interval 89.63 to 99.64	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, and 36

Population: The PPAMI included all participants who received any study injection, who did not have major protocol deviations that impacted AMI response, and who complied with the injection schedule and timing of immunogenicity blood sampling to have post-injection results available for at least 1 assay component of AMI at the corresponding visit. 'Overall number of participants analyzed' = participants evaluable for this outcome measure. 'Number analyzed' = participants evaluable for specified categories.

Seroresponse was defined as an increase in ZIKV-specific nAb titer from below the LLOQ to greater than or equal to the LLOQ. LLOQ=91; ULOQ=24814.

Outcome measures

Outcome measures
Measure	Placebo n=76 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=70 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=81 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=93 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-negative Participants by PRNT50	0 percentage of participants Interval 0.0 to 4.8	0 percentage of participants Interval 0.0 to 5.13	2.5 percentage of participants Interval 0.3 to 8.64	1.1 percentage of participants Interval 0.03 to 6.04	—	—	—	—
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-negative Participants by PRNT50	1.3 percentage of participants Interval 0.03 to 7.11	8.7 percentage of participants Interval 3.26 to 17.97	25.9 percentage of participants Interval 16.82 to 36.86	1.1 percentage of participants Interval 0.03 to 6.04	—	—	—	—
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-negative Participants by PRNT50	0 percentage of participants Interval 0.0 to 4.74	88.6 percentage of participants Interval 78.72 to 94.93	78.8 percentage of participants Interval 68.17 to 87.11	2.2 percentage of participants Interval 0.27 to 7.88	—	—	—	—
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-negative Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.8	0 percentage of participants Interval 0.0 to 5.13	1.2 percentage of participants Interval 0.03 to 6.69	0 percentage of participants Interval 0.0 to 4.02	—	—	—	—
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-negative Participants by PRNT80	1.3 percentage of participants Interval 0.03 to 7.11	2.9 percentage of participants Interval 0.35 to 10.08	7.4 percentage of participants Interval 2.77 to 15.43	0 percentage of participants Interval 0.0 to 4.02	—	—	—	—
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, and 36, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-negative Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.74	77.1 percentage of participants Interval 65.55 to 86.33	71.3 percentage of participants Interval 60.05 to 80.82	0 percentage of participants Interval 0.0 to 4.06	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, 36, and 57

Population: The PPAMI included all participants who received any study injection, who did not have major protocol deviations that impacted AMI response, and who complied with the injection schedule and timing of immunogenicity blood sampling to have post-injection results available for at least 1 assay component of AMI at the corresponding visit. 'Overall number of participants analyzed' = participants evaluable for this outcome measure. 'Number analyzed' = participants evaluable for specified categories.

Seroresponse was defined as an increase in ZIKV-specific nAb titer from below the LLOQ to greater than or equal to the LLOQ. LLOQ=28; ULOQ=11589.

Outcome measures

Outcome measures
Measure	Placebo n=76 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=69 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=81 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=90 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, 36, and 57, as Measured by MN Day 8: Flavivirus-negative Participants	0 percentage of participants Interval 0.0 to 4.8	5.8 percentage of participants Interval 1.6 to 14.18	16.0 percentage of participants Interval 8.83 to 25.88	0 percentage of participants Interval 0.0 to 4.02	—	—	—	—
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, 36, and 57, as Measured by MN Day 29: Flavivirus-negative Participants	0 percentage of participants Interval 0.0 to 4.74	97.1 percentage of participants Interval 89.78 to 99.64	95.1 percentage of participants Interval 87.84 to 98.64	1.1 percentage of participants Interval 0.03 to 6.04	—	—	—	—
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, 36, and 57, as Measured by MN Day 36: Flavivirus-negative Participants	0 percentage of participants Interval 0.0 to 4.74	98.6 percentage of participants Interval 92.19 to 99.96	97.5 percentage of participants Interval 91.26 to 99.7	15.7 percentage of participants Interval 8.88 to 24.98	—	—	—	—
Percentage of Initially Seronegative Participants With a Seroresponse at Days 8, 29, 36, and 57, as Measured by MN Day 57: Flavivirus-negative Participants	0 percentage of participants Interval 0.0 to 4.74	98.6 percentage of participants Interval 92.19 to 99.96	100.0 percentage of participants Interval 95.55 to 100.0	94.4 percentage of participants Interval 87.51 to 98.17	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, 36, and 57

Population: The PPAMI included all participants who received any study injection, who did not have major protocol deviations that impacted AMI response, and who complied with the injection schedule and timing of immunogenicity blood sampling to have post-injection results available for at least 1 assay component of AMI at the corresponding visit. 'Overall number of participants analyzed' = participants evaluable for this outcome measure. 'Number analyzed' = participants evaluable for specified categories.

≥2-fold increase from baseline was defined as a ≥2 \* LLOQ for participants with baseline undetectable antibody titer, or a 2-times or higher ratio in participants with pre-existing nAb titers. LLOQ=91

Outcome measures

Outcome measures
Measure	Placebo n=86 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=87 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=79 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=67 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT50	8.1 percentage of participants Interval 3.34 to 16.05	41.4 percentage of participants Interval 30.92 to 52.45	38.5 percentage of participants Interval 27.66 to 50.17	6.1 percentage of participants Interval 1.68 to 14.8	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT50	10.5 percentage of participants Interval 4.9 to 18.94	55.2 percentage of participants Interval 44.13 to 65.85	44.3 percentage of participants Interval 33.12 to 55.92	6.0 percentage of participants Interval 1.65 to 14.59	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT50	4.7 percentage of participants Interval 1.3 to 11.61	60.9 percentage of participants Interval 49.87 to 71.21	63.3 percentage of participants Interval 51.69 to 73.86	46.3 percentage of participants Interval 34.0 to 58.88	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 57: Flavivirus-positive Participants by PRNT50	5.8 percentage of participants Interval 1.91 to 13.05	63.2 percentage of participants Interval 52.2 to 73.31	63.3 percentage of participants Interval 51.69 to 73.86	62.7 percentage of participants Interval 50.01 to 74.2	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.2	40.2 percentage of participants Interval 29.85 to 51.29	38.5 percentage of participants Interval 27.66 to 50.17	4.5 percentage of participants Interval 0.95 to 12.71	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.2	49.4 percentage of participants Interval 38.53 to 60.36	43.0 percentage of participants Interval 31.94 to 54.67	1.5 percentage of participants Interval 0.04 to 8.04	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT80	1.2 percentage of participants Interval 0.03 to 6.38	63.2 percentage of participants Interval 52.2 to 73.31	62.0 percentage of participants Interval 50.41 to 72.72	50.7 percentage of participants Interval 38.24 to 63.18	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 57: Flavivirus-positive Participants by PRNT80	3.5 percentage of participants Interval 0.73 to 9.86	63.2 percentage of participants Interval 52.2 to 73.31	60.8 percentage of participants Interval 49.13 to 71.56	61.2 percentage of participants Interval 48.5 to 72.86	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, 36, and 57

Population: The PPAMI included all participants who received any study injection, who did not have major protocol deviations that impacted AMI response, and who complied with the injection schedule and timing of immunogenicity blood sampling to have post-injection results available for at least 1 assay component of AMI at the corresponding visit. 'Overall number of participants analyzed' = participants evaluable for this outcome measure. 'Number analyzed' = participants evaluable for specified categories.

≥4-fold increase from baseline was defined as a ≥4 \* LLOQ for participants with baseline undetectable antibody titer, or a 4-times or higher ratio in participants with pre-existing nAb titers. LLOQ=91

Outcome measures

Outcome measures
Measure	Placebo n=86 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=87 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=79 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=67 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT50	2.3 percentage of participants Interval 0.28 to 8.15	35.6 percentage of participants Interval 25.65 to 46.62	35.9 percentage of participants Interval 25.34 to 47.56	4.5 percentage of participants Interval 0.95 to 12.71	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT50	7.0 percentage of participants Interval 2.6 to 14.57	42.5 percentage of participants Interval 31.99 to 53.59	40.5 percentage of participants Interval 29.6 to 52.15	4.5 percentage of participants Interval 0.93 to 12.53	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT50	1.2 percentage of participants Interval 0.03 to 6.38	50.6 percentage of participants Interval 39.64 to 61.47	50.6 percentage of participants Interval 39.14 to 62.08	38.8 percentage of participants Interval 27.14 to 51.5	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 57: Flavivirus-positive Participants by PRNT50	2.3 percentage of participants Interval 0.28 to 8.15	52.9 percentage of participants Interval 41.87 to 63.67	48.1 percentage of participants Interval 36.71 to 59.64	47.8 percentage of participants Interval 35.4 to 60.33	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 8: Flavivirus-positive Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.2	35.6 percentage of participants Interval 25.65 to 46.62	33.3 percentage of participants Interval 23.06 to 44.92	1.5 percentage of participants Interval 0.04 to 8.16	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 29: Flavivirus-positive Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.2	40.2 percentage of participants Interval 29.85 to 51.29	38.0 percentage of participants Interval 27.28 to 49.59	0 percentage of participants Interval 0.0 to 5.36	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 36: Flavivirus-positive Participants by PRNT80	0 percentage of participants Interval 0.0 to 4.25	50.6 percentage of participants Interval 39.64 to 61.47	50.6 percentage of participants Interval 39.14 to 62.08	43.3 percentage of participants Interval 31.22 to 55.96	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by PRNT50 and PRNT80 Day 57: Flavivirus-positive Participants by PRNT80	1.2 percentage of participants Interval 0.03 to 6.31	50.6 percentage of participants Interval 39.64 to 61.47	43.0 percentage of participants Interval 31.94 to 54.67	49.3 percentage of participants Interval 36.82 to 61.76	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, 36, and 57

Population: The PPAMI included all participants who received any study injection, who did not have major protocol deviations that impacted AMI response, and who complied with the injection schedule and timing of immunogenicity blood sampling to have post-injection results available for at least 1 assay component of AMI at the corresponding visit. 'Overall number of participants analyzed' = participants evaluable for this outcome measure. 'Number analyzed' = participants evaluable for specified categories.

Outcome measures

Outcome measures
Measure	Placebo n=86 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=87 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=79 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=67 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by MN Day 8: Flavivirus-positive Participants	3.5 percentage of participants Interval 0.73 to 9.86	58.6 percentage of participants Interval 47.55 to 69.08	63.3 percentage of participants Interval 51.69 to 73.86	4.5 percentage of participants Interval 0.93 to 12.53	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by MN Day 29: Flavivirus-positive Participants	2.3 percentage of participants Interval 0.28 to 8.15	87.4 percentage of participants Interval 78.5 to 93.52	96.2 percentage of participants Interval 89.3 to 99.21	0 percentage of participants Interval 0.0 to 5.36	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by MN Day 36: Flavivirus-positive Participants	4.7 percentage of participants Interval 1.3 to 11.61	92.0 percentage of participants Interval 84.12 to 96.7	97.5 percentage of participants Interval 91.15 to 99.69	71.6 percentage of participants Interval 59.31 to 81.99	—	—	—	—
Percentage of Initially Seropositive Participants With a 2-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by MN Day 57: Flavivirus-positive Participants	2.3 percentage of participants Interval 0.28 to 8.15	97.7 percentage of participants Interval 91.94 to 99.72	98.7 percentage of participants Interval 93.15 to 99.97	100.0 percentage of participants Interval 94.64 to 100.0	—	—	—	—

SECONDARY outcome

Timeframe: Days 8, 29, 36, and 57

Population: The PPAMI included all participants who received any study injection, who did not have major protocol deviations that impacted AMI response, and who complied with the injection schedule and timing of immunogenicity blood sampling to have post-injection results available for at least 1 assay component of AMI at the corresponding visit. 'Overall number of participants analyzed' = participants evaluable for this outcome measure. 'Number analyzed' = participants evaluable for specified categories.

Outcome measures

Outcome measures
Measure	Placebo n=86 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=87 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=79 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=67 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) Participants were followed up for up to Day 700 in the extension period.
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by MN Day 8: Flavivirus-positive Participants	2.3 percentage of participants Interval 0.28 to 8.15	43.7 percentage of participants Interval 33.06 to 54.74	50.6 percentage of participants Interval 39.14 to 62.08	1.5 percentage of participants Interval 0.04 to 8.04	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by MN Day 29: Flavivirus-positive Participants	2.3 percentage of participants Interval 0.28 to 8.15	79.3 percentage of participants Interval 69.29 to 87.25	87.3 percentage of participants Interval 77.95 to 93.76	0 percentage of participants Interval 0.0 to 5.36	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by MN Day 36: Flavivirus-positive Participants	1.2 percentage of participants Interval 0.03 to 6.38	81.6 percentage of participants Interval 71.86 to 89.11	92.4 percentage of participants Interval 84.2 to 97.16	58.2 percentage of participants Interval 45.52 to 70.15	—	—	—	—
Percentage of Initially Seropositive Participants With a 4-Fold Increase in ZIKV-Specific nAb Titers as Compared With Baseline, as Measured by MN Day 57: Flavivirus-positive Participants	2.3 percentage of participants Interval 0.28 to 8.15	93.1 percentage of participants Interval 85.59 to 97.43	93.7 percentage of participants Interval 85.84 to 97.91	92.5 percentage of participants Interval 83.44 to 97.53	—	—	—	—

OTHER_PRE_SPECIFIED outcome

Timeframe: Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period

Population: The Randomized Set included all participants who were randomized in the study, regardless of the participant's treatment status in the study. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set for collection and reporting data.

A death that occurred during the study or that came to the attention of the investigator during the study was reported to the Sponsor, irrespective of its perceived relationship to the study drug. The Investigator assessed the causality by determining whether there was a reasonable possibility that the death was related to the study drug, using the following classifications: Not related: There was not a reasonable possibility of a relationship to the study drug. The temporal sequence of the death relative to administration of the study drug was not reasonable AND/OR the death was more likely explained by a cause other than the study drug. Related: There was a reasonable possibility of a relationship to the study drug. There was evidence of exposure to the study drug. The temporal sequence of the death relative to the administration of the study drug was reasonable.

Outcome measures

Outcome measures
Measure	Placebo n=203 Participants Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 Low Dose (2-Dose Regimen) n=202 Participants Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (2-Dose Regimen) n=203 Participants Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	mRNA-1893 High Dose (1-Dose Regimen) n=201 Participants Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo n=113 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) n=109 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) n=104 Participants Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) n=116 Participants Participants were followed up for up to Day 700 in the extension period.
Number of Deaths Related to Study Drug Deaths	0 Participants	0 Participants	0 Participants	1 Participants	0 Participants	1 Participants	0 Participants	0 Participants
Number of Deaths Related to Study Drug Deaths Related to Study Drug	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants

Adverse Events

Main Study: Placebo

Serious events: 5 serious events

Other events: 18 other events

Deaths: 0 deaths

Main Study: mRNA-1893 Low Dose (2-Dose Regimen)

Serious events: 2 serious events

Other events: 20 other events

Deaths: 0 deaths

Main Study: mRNA-1893 High Dose (2-Dose Regimen)

Serious events: 4 serious events

Other events: 24 other events

Deaths: 0 deaths

Main Study: mRNA-1893 High Dose (1-Dose Regimen)

Serious events: 7 serious events

Other events: 16 other events

Deaths: 1 deaths

Extension Period: Placebo

Serious events: 5 serious events

Other events: 8 other events

Deaths: 0 deaths

Extension Period: mRNA-1893 Low Dose (2-Dose Regimen)

Serious events: 4 serious events

Other events: 5 other events

Deaths: 1 deaths

Extension Period: mRNA-1893 High Dose (2-Dose Regimen)

Serious events: 5 serious events

Other events: 8 other events

Deaths: 0 deaths

Extension Period: mRNA-1893 High Dose (1-Dose Regimen)

Serious events: 7 serious events

Other events: 10 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	Main Study: Placebo n=201 participants at risk Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	Main Study: mRNA-1893 Low Dose (2-Dose Regimen) n=202 participants at risk Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	Main Study: mRNA-1893 High Dose (2-Dose Regimen) n=202 participants at risk Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	Main Study: mRNA-1893 High Dose (1-Dose Regimen) n=198 participants at risk Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo n=113 participants at risk Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) n=109 participants at risk Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) n=104 participants at risk Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) n=116 participants at risk Participants were followed up for up to Day 700 in the extension period.
Infections and infestations Cellulitis	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.96% 1/104 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.86% 1/116 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Infections and infestations Diabetic foot infection	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.96% 1/104 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Infections and infestations Large intestine infection	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.86% 1/116 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Infections and infestations Localised infection	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.50% 1/202 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Infections and infestations Pneumonia	0.50% 1/201 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Breast cancer	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.92% 1/109 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Meningioma	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.96% 1/104 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Uterine leiomyoma	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.50% 1/202 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Metabolism and nutrition disorders Hypokalaemia	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.51% 1/198 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Metabolism and nutrition disorders Type 2 diabetes mellitus	0.50% 1/201 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Psychiatric disorders Alcohol withdrawal syndrome	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.86% 1/116 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Psychiatric disorders Depression	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.51% 1/198 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Psychiatric disorders Factitious disorder	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.51% 1/198 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Psychiatric disorders Major depression	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.88% 1/113 • Number of events 2 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Nervous system disorders Transient ischaemic attack	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.50% 1/202 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Cardiac disorders Myocardial infarction	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.51% 1/198 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Respiratory, thoracic and mediastinal disorders Dyspnoea	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.50% 1/202 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Respiratory, thoracic and mediastinal disorders Pneumothorax	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.92% 1/109 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Gastrointestinal disorders Hiatus hernia	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.51% 1/198 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Hepatobiliary disorders Cholecystitis	0.50% 1/201 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Hepatobiliary disorders Cholecystitis acute	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.86% 1/116 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Musculoskeletal and connective tissue disorders Arthralgia	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.50% 1/202 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Musculoskeletal and connective tissue disorders Intervertebral disc degeneration	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.92% 1/109 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.86% 1/116 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Musculoskeletal and connective tissue disorders Lumbar spinal stenosis	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.88% 1/113 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Musculoskeletal and connective tissue disorders Osteoarthritis	0.50% 1/201 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.88% 1/113 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Musculoskeletal and connective tissue disorders Rotator cuff tear arthropathy	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.96% 1/104 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Musculoskeletal and connective tissue disorders Spondylolisthesis	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.88% 1/113 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Renal and urinary disorders Acute kidney injury	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.86% 1/116 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Renal and urinary disorders Renal colic	0.50% 1/201 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Renal and urinary disorders Ureterolithiasis	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.50% 1/202 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.88% 1/113 • Number of events 2 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Pregnancy, puerperium and perinatal conditions Abortion spontaneous	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.88% 1/113 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Congenital, familial and genetic disorders BRCA1 gene mutation	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.92% 1/109 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Congenital, familial and genetic disorders Heart disease congenital	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.96% 1/104 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Congenital, familial and genetic disorders Trisomy 21	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.96% 1/104 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
General disorders Death	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.92% 1/109 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
General disorders Oedema peripheral	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.88% 1/113 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Injury, poisoning and procedural complications Alcohol poisoning	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.51% 1/198 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Injury, poisoning and procedural complications Ankle fracture	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.51% 1/198 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.86% 1/116 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Injury, poisoning and procedural complications Burns second degree	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.92% 1/109 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/104 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Injury, poisoning and procedural complications Spinal compression fracture	0.00% 0/201 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/202 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/198 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/113 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.96% 1/104 • Number of events 1 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/116 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.

Other adverse events

Other adverse events
Measure	Main Study: Placebo n=201 participants at risk Participants received placebo matched to mRNA-1893 administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	Main Study: mRNA-1893 Low Dose (2-Dose Regimen) n=202 participants at risk Participants received mRNA-1893 at a low dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	Main Study: mRNA-1893 High Dose (2-Dose Regimen) n=202 participants at risk Participants received mRNA-1893 at a high dose level administered as a 2-dose regimen with 28-day interval between vaccinations (administered on Day 1 and Day 29).	Main Study: mRNA-1893 High Dose (1-Dose Regimen) n=198 participants at risk Participants received placebo matched to mRNA-1893 on Day 1 and mRNA-1893 at a high dose level administered as a 1-dose regimen (administered on Day 29). There was 28-day interval between vaccinations.	Extension Period: Placebo n=113 participants at risk Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 Low Dose (2-Dose Regimen) n=109 participants at risk Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (2-Dose Regimen) n=104 participants at risk Participants were followed up for up to Day 700 in the extension period.	Extension Period: mRNA-1893 High Dose (1-Dose Regimen) n=116 participants at risk Participants were followed up for up to Day 700 in the extension period.
Infections and infestations COVID-19	6.0% 12/201 • Number of events 12 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	6.4% 13/202 • Number of events 13 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	10.9% 22/202 • Number of events 23 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	6.1% 12/198 • Number of events 12 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	2.7% 3/113 • Number of events 3 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.00% 0/109 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	2.9% 3/104 • Number of events 3 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	5.2% 6/116 • Number of events 6 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.
Infections and infestations Upper respiratory tract infection	3.0% 6/201 • Number of events 6 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	4.0% 8/202 • Number of events 8 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	0.99% 2/202 • Number of events 2 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	2.5% 5/198 • Number of events 6 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	5.3% 6/113 • Number of events 6 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	4.6% 5/109 • Number of events 5 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	4.8% 5/104 • Number of events 7 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.	3.4% 4/116 • Number of events 4 • All-cause mortality and serious adverse events were collected from Day 1 through Day 196 for Main Study and Day 197 through Day 700 for Extension Period. Other (not including serious) unsolicited adverse events were collected up to 28 days after study injection (that is, Day 1 up to Day 57) unless they met the criteria for AESIs, MAAEs or AEs led to discontinuation. The all-cause mortality was based on the randomized set. The serious and other (not including serious) adverse events were based on the safety set which consisted of all randomized participants who received any study injection. One participant who was randomized at two sites and received two injections was kept in both arms (Randomized to mRNA-1893 High Dose \[2-Dose Regimen\] and mRNA-1893 Low Dose \[2-Dose Regimen\]) in Randomized Set and Safety Set for collection and reporting data.

Additional Information

Moderna WeCare Team

ModernaTX, Inc.

Phone: +1-866-663-3762

Email: [email protected]

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