Trial Outcomes & Findings for A Study to Evaluate Safety and Immunogenicity of mRNA-1273 Vaccine to Prevent COVID-19 in Adult Organ Transplant Recipients and in Healthy Adult Participants (NCT NCT04860297)

Last Updated: 2024-06-18

Results Overview

An unsolicited AE was any AE reported by the participant that was not specified as a solicited AR or was specified as a solicited AR but started outside the protocol-defined period for reporting solicited ARs (that is, for the 7 days after each dose of vaccine). A summary of SAEs and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section.

Recruitment status

COMPLETED

Study phase

PHASE3

Target enrollment

234 participants

Primary outcome timeframe

Up to 28 days post-vaccination

Results posted on

2024-06-18

Participant Flow

A total of 214 solid organ transplant (SOT) participants (137 SOT kidney and 77 SOT liver participants) and 20 healthy participants were enrolled for the study.

Healthy participants cohort was included as a control group in the evaluation of humoral and cell-mediated immune response only; no comparisons of safety data with the healthy participants were made. Data reported for each arm in the Outcome Measures as specified in the Outcome Measure title.

Participant milestones

Participant milestones
Measure	Part A (Primary Series): Cohort A1 - SOT Participants Unvaccinated SOT participants received 2 100-micrograms (μg) doses of mRNA-1273 vaccine by intramuscular (IM) injection, 28 days apart (on Day 1 and Day 29).	Part A (Primary Series): Cohort A2 - SOT Participants Unvaccinated SOT participants received 3 100-μg doses of mRNA-1273 vaccine by IM injection, on Day 1 and Day 29 (28 days apart) and on Day 85 (56 days after Dose 2).	Part A (Primary Series): Cohort A3 - SOT Participants Previously vaccinated SOT participants with 2 doses of Moderna COVID-19 vaccine outside the study received a single 100-μg dose (Dose 3) on Day 1.	Part A (Primary Series): Cohort A5 - Healthy Participants Healthy participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29).	Part B (Booster Dose): Cohort B2 - SOT Participants Unvaccinated SOT participants who received 3 doses of mRNA-1273 vaccine in Part A (Days 1, 29, and 85), received a 100-μg booster dose (BD) of mRNA-1273 vaccine on BD DAY 1.	Part B (Booster Dose): Cohort B3 - SOT Participants Previously vaccinated SOT participants with 2 doses of Moderna COVID-19 vaccine outside the study who received a single 100-μg dose (Dose 3) on Day 1 in Part A, received a 100-μg BD of mRNA-1273 vaccine on BD Day 1.	Part B (Booster Dose): Cohort B4 - SOT Participants SOT participants who completed primary vaccination with an mRNA or non-mRNA- COVID-19 vaccine outside mRNA-1273-P304, received a 100-μg BD of mRNA-1273 vaccine on BD Day 1.	Part B (Booster Dose): Cohort B5 - Healthy Participants Healthy participants who received 2 doses of mRNA-1273 vaccine in Part A (Days 1 and 29), received a 100-μg BD of mRNA-1273 vaccine on BD Day 1.
Part A (Primary Series) STARTED	3	58	71	20	0	0	0	0
Part A (Primary Series) Received First Study Injection	3	58	0	20	0	0	0	0
Part A (Primary Series) Received Second Study Injection	3	58	0	0	0	0	0	0
Part A (Primary Series) Received Third Study Injection	0	57	71	0	0	0	0	0
Part A (Primary Series) COMPLETED	2	57	71	17	0	0	0	0
Part A (Primary Series) NOT COMPLETED	1	1	0	3	0	0	0	0
Part B (Booster Dose) STARTED	0	0	0	0	33	44	82	10
Part B (Booster Dose) Received Booster Injection	0	0	0	0	33	44	81	10
Part B (Booster Dose) COMPLETED	0	0	0	0	29	34	78	7
Part B (Booster Dose) NOT COMPLETED	0	0	0	0	4	10	4	3

Reasons for withdrawal

Reasons for withdrawal
Measure	Part A (Primary Series): Cohort A1 - SOT Participants Unvaccinated SOT participants received 2 100-micrograms (μg) doses of mRNA-1273 vaccine by intramuscular (IM) injection, 28 days apart (on Day 1 and Day 29).	Part A (Primary Series): Cohort A2 - SOT Participants Unvaccinated SOT participants received 3 100-μg doses of mRNA-1273 vaccine by IM injection, on Day 1 and Day 29 (28 days apart) and on Day 85 (56 days after Dose 2).	Part A (Primary Series): Cohort A5 - Healthy Participants Healthy participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29).	Part B (Booster Dose): Cohort B2 - SOT Participants Unvaccinated SOT participants who received 3 doses of mRNA-1273 vaccine in Part A (Days 1, 29, and 85), received a 100-μg booster dose (BD) of mRNA-1273 vaccine on BD DAY 1.	Part B (Booster Dose): Cohort B3 - SOT Participants Previously vaccinated SOT participants with 2 doses of Moderna COVID-19 vaccine outside the study who received a single 100-μg dose (Dose 3) on Day 1 in Part A, received a 100-μg BD of mRNA-1273 vaccine on BD Day 1.	Part B (Booster Dose): Cohort B4 - SOT Participants SOT participants who completed primary vaccination with an mRNA or non-mRNA- COVID-19 vaccine outside mRNA-1273-P304, received a 100-μg BD of mRNA-1273 vaccine on BD Day 1.	Part B (Booster Dose): Cohort B5 - Healthy Participants Healthy participants who received 2 doses of mRNA-1273 vaccine in Part A (Days 1 and 29), received a 100-μg BD of mRNA-1273 vaccine on BD Day 1.
Part A (Primary Series) Withdrawal by Subject	0	1	1	0	0	0	0
Part A (Primary Series) Lost to Follow-up	1	0	2	0	0	0	0
Part B (Booster Dose) Protocol Deviation	0	0	0	0	0	1	0
Part B (Booster Dose) Other Than Specified	0	0	0	0	1	1	0
Part B (Booster Dose) Withdrawal by Subject	0	0	0	0	2	0	1
Part B (Booster Dose) Death	0	0	0	1	2	1	0
Part B (Booster Dose) Lost to Follow-up	0	0	0	3	5	1	2

Baseline Characteristics

A Study to Evaluate Safety and Immunogenicity of mRNA-1273 Vaccine to Prevent COVID-19 in Adult Organ Transplant Recipients and in Healthy Adult Participants

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Healthy Participants n=20 Participants Healthy participants received 2 doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Total n=234 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
Age, Categorical Between 18 and 65 years	108 Participants n=5 Participants	58 Participants n=7 Participants	18 Participants n=5 Participants	184 Participants n=4 Participants
Age, Categorical >=65 years	29 Participants n=5 Participants	19 Participants n=7 Participants	2 Participants n=5 Participants	50 Participants n=4 Participants
Sex: Female, Male Female	62 Participants n=5 Participants	38 Participants n=7 Participants	10 Participants n=5 Participants	110 Participants n=4 Participants
Sex: Female, Male Male	75 Participants n=5 Participants	39 Participants n=7 Participants	10 Participants n=5 Participants	124 Participants n=4 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	15 Participants n=5 Participants	5 Participants n=7 Participants	2 Participants n=5 Participants	22 Participants n=4 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	121 Participants n=5 Participants	71 Participants n=7 Participants	18 Participants n=5 Participants	210 Participants n=4 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	1 Participants n=5 Participants	1 Participants n=7 Participants	0 Participants n=5 Participants	2 Participants n=4 Participants
Race (NIH/OMB) American Indian or Alaska Native	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants	2 Participants n=4 Participants
Race (NIH/OMB) Asian	8 Participants n=5 Participants	3 Participants n=7 Participants	2 Participants n=5 Participants	13 Participants n=4 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) Black or African American	23 Participants n=5 Participants	13 Participants n=7 Participants	3 Participants n=5 Participants	39 Participants n=4 Participants
Race (NIH/OMB) White	94 Participants n=5 Participants	55 Participants n=7 Participants	11 Participants n=5 Participants	160 Participants n=4 Participants
Race (NIH/OMB) More than one race	1 Participants n=5 Participants	2 Participants n=7 Participants	0 Participants n=5 Participants	3 Participants n=4 Participants
Race (NIH/OMB) Unknown or Not Reported	10 Participants n=5 Participants	4 Participants n=7 Participants	3 Participants n=5 Participants	17 Participants n=4 Participants

PRIMARY outcome

Timeframe: Up to 28 days post-vaccination

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

An unsolicited AE was any AE reported by the participant that was not specified as a solicited adverse reaction (AR) or was specified as a solicited AR but started outside the protocol-defined period for reporting solicited ARs (that is, for the 7 days after each dose of vaccine). A summary of serious adverse events (SAEs) and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=214 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of SOT Participants With Unsolicited Adverse Events (AEs)	48 Participants	41 Participants	89 Participants	—

PRIMARY outcome

Timeframe: Up to 28 days post-vaccination

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=20 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of Healthy Participants With Unsolicited AEs	12 Participants	—	—	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 450)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

An MAAE was an AE that led to an unscheduled visit to an healthcare practitioner (HCP). This included visits to a study site for unscheduled assessments (for example, abnormal laboratory test results follow-up, COVID-19) and visits to HCPs external to the study site (for example, urgent care, primary care physician). MAAEs were also required by protocol for routine surveillance of participants with symptoms for COVID-19 infection (fever, shortness of breath, cough, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or runny nose, nausea or vomiting, and diarrhea). All confirmed symptomatic COVID-19 cases were recorded as MAAEs. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=214 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of SOT Participants With Medically-Attended Adverse Events (MAAEs)	86 Participants	56 Participants	142 Participants	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 394)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

An MAAE was an AE that led to an unscheduled visit to an HCP. This included visits to a study site for unscheduled assessments (for example, abnormal laboratory test results follow-up, COVID-19) and visits to HCPs external to the study site (for example, urgent care, primary care physician). MAAEs were also required by protocol for routine surveillance of participants with symptoms for COVID-19 infection (fever, shortness of breath, cough, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or runny nose, nausea or vomiting, and diarrhea). All confirmed symptomatic COVID-19 cases were recorded as MAAEs. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=20 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of Healthy Participants With MAAEs	14 Participants	—	—	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 450)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

An AE (including an AR) was considered an SAE if, in the view of either the investigator or Sponsor, it results in any of the following outcomes: death, was life-threatening, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, congenital anomaly or birth defect, or medically important event. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=214 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of SOT Participants With Serious Adverse Events (SAEs)	29 Participants	19 Participants	48 Participants	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 394)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=20 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of Healthy Participants With SAEs	1 Participants	—	—	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 450)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

An AESI was an AE (serious or non-serious) of scientific and medical concern specific to the Sponsor's product or program. AESIs included thrombocytopenia, new onset of or worsening of the protocol specified neurologic diseases, anaphylaxis, and myocarditis/pericarditis. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=214 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of SOT Participants With Adverse Event of Special Interests (AESIs), Including Myocarditis/Pericarditis	15 Participants	13 Participants	28 Participants	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 394)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=20 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of Healthy Participants With AESIs, Including Myocarditis/Pericarditis	1 Participants	—	—	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 450)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not it is considered drug-related. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=214 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of SOT Participants With AEs Leading to Discontinuation From Dosing and/or Study Participation (Withdrawal)	4 Participants	0 Participants	4 Participants	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 394)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=20 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of Healthy Participants With AEs Leading to Discontinuation From Dosing and/or Study Participation (Withdrawal)	0 Participants	—	—	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 450)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=214 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of SOT Participants With Adjudicated Biopsy-Proven Organ Rejection	1 Participants	2 Participants	3 Participants	—

PRIMARY outcome

Timeframe: Throughout the study period (up to Day 394)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=20 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of Healthy Participants With Biopsy-Proven Organ Rejection	0 Participants	—	—	—

PRIMARY outcome

Timeframe: 7 days post-vaccination

Population: Any study injection solicited safety set included all participants who received any (first, second, third, or booster) study injection and contributed any solicited AR data following that injection. Here, 'Number analyzed' signifies participants evaluable for the specified category.

Solicited ARs, including local and systemic ARs were collected in the eDiary. Local ARs included: pain at injection site, erythema (redness) at injection site, swelling/induration (hardness) at injection site, and localized axillary swelling or tenderness ipsilateral to the injection arm. Systemic ARs included: headache, fatigue, myalgia (muscle aches all over the body), arthralgia (aching in several joints), nausea/vomiting, rash, body temperature (potentially fever), and chills. All solicited ARs (local and systemic) considered causally related to injection. ARs were graded 0-4 as reviewed and confirmed by Investigator; lower score indicates lower severity and a higher score indicates greater severity. Note, not all solicited ARs were considered AEs. The Investigator reviewed whether the solicited AR was also to be recorded as an AE. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=214 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of SOT Participants With Solicited Local and Systemic Adverse Reactions (ARs) Solicited Local ARs	116 Participants	65 Participants	181 Participants	—
Parts A and B: Number of SOT Participants With Solicited Local and Systemic Adverse Reactions (ARs) Solicited Systemic ARs	102 Participants	70 Participants	172 Participants	—

PRIMARY outcome

Timeframe: 7 days post-vaccination

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=20 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of Healthy Participants With Solicited Local and Systemic ARs Solicited Local ARs	16 Participants	—	—	—
Parts A and B: Number of Healthy Participants With Solicited Local and Systemic ARs Solicited Systemic ARs	19 Participants	—	—	—

PRIMARY outcome

Timeframe: Day 57 (for unvaccinated participants)

Population: The per protocol (PP) immunogenicity set (Part A) included all participants who received at least 1 dose of study drug, had no immunologic/virologic evidence of prior COVID-19 at baseline/pre-vaccination, had post-injection results available for at least 1 assay component corresponding to the immunogenicity analysis objective, and had no major protocol deviations that impacted immune response. 'Overall number of participants analyzed' = participants analyzed for this outcome measure.

The GMC of VAC62 antibodies, as measured by pseudovirus neutralization assay (PsVNA) specific to the SARS-CoV-2 spike protein is reported. 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 if actual values were not available. LLOQ was 10 and ULOQ was 111433 arbitrary units (AU)/milliliter (mL). The 95% confidence intervals (CIs) were calculated based on the t-distribution of the log-transformed values or the difference in the log-transformed values for GMC value, then back transformed to the original scale for presentation. Results in healthy participants were included as reference not for any comparisons.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=23 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=13 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=16 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Geometric Mean Concentration (GMC) of Serum SARS-CoV-2-Specific Neutralizing Antibody (nAb) After the Second Dose in Unvaccinated Participants	54.2 AU/mL Interval 23.4 to 125.5	187.9 AU/mL Interval 67.6 to 522.6	1658.4 AU/mL Interval 951.1 to 2891.6	—

PRIMARY outcome

Timeframe: 28 days after Dose 3

Population: The PP immunogenicity set (Part A) included all participants who received at least 1 dose of study drug, had no immunologic/virologic evidence of prior COVID-19 at baseline/pre-vaccination, had post-injection results available for at least 1 assay component corresponding to the immunogenicity analysis objective, and had no major protocol deviations that impacted immune response. 'Overall number of participants analyzed' = participants analyzed for this outcome measure.

The GMC of VAC62 antibodies, as measured by PsVNA specific to the SARS-CoV-2 spike protein is reported. 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 if actual values were not available. LLOQ was 10 and ULOQ was 111433 AU/mL. The 95% CIs were calculated based on the t-distribution of the log-transformed values or the difference in the log-transformed values for GMC value, then back transformed to the original scale for presentation.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=52 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=24 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=76 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: GMC of SARS-CoV-2-Specific nAb 28 Days After Dose 3	353.5 AU/mL Interval 171.2 to 729.7	1340.2 AU/mL Interval 617.4 to 2909.1	538.4 AU/mL Interval 307.2 to 943.7	—

PRIMARY outcome

Timeframe: 28 days after BD injection (BD-Day 29)

Population: The PP set (Part B) included all participants who received BD of study drug, had no immunologic or virologic evidence of prior COVID-19 at pre-booster before the BD, had post-booster results available for at least 1 assay component corresponding to the immunogenicity analysis objective, and had no major protocol deviations that impacted immune response during the period corresponding to the immunogenicity analysis objective.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=62 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=31 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part B: GMC of SARS-CoV-2-Specific nAb 28 Days After the BD in SOT Participants Who Received the Moderna Primary Series and Non-Moderna Primary Series	430.7 AU/mL Interval 216.4 to 857.5	3946.0 AU/mL Interval 1944.5 to 8007.8	—	—

SECONDARY outcome

Timeframe: Days 1, 28 days after Dose 1, 28 days after Dose 2, 6 months after Dose 2, and 1 year after Dose 2

Population: PP immunogenicity set (Part A): all participants who received at least 1 dose of study drug, had no immunologic/virologic evidence of prior COVID-19 at baseline, had post-injection results available for at least 1 assay component corresponding to immunogenicity analysis, and had no major protocol deviations that impacted immune response. 'Overall number of participants analyzed' = participants analyzed for this outcome measure. 'Number analyzed' = participants evaluable at specified timepoint.

The GMC of VAC62 antibodies, as measured by pseudovirus neutralization assay PsVNA specific to the SARS-CoV-2 spike protein is reported. Antibody values reported as below the LLOQ were replaced by 0.5\*LLOQ. Values that were greater than the ULOQ were replaced by the ULOQ if actual values were not available. LLOQ was 10 and ULOQ was 111433 AU/mL. The 95% CIs were calculated based on the t-distribution of the log-transformed values or the difference in the log-transformed values for GMC value, then back transformed to the original scale for presentation. Results in healthy participants were included as reference not for any comparisons. 95% CI cannot be calculated with an 'N' less than 2.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=24 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=14 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=16 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: GMC of SARS-CoV-2-Specific nAb for Unvaccinated Participants Receiving the 2-Dose Regimen Day 1	13.9 AU/mL Interval 10.1 to 19.2	13.6 AU/mL Interval 8.0 to 23.2	11.2 AU/mL Interval 7.3 to 17.1	—
Part A: GMC of SARS-CoV-2-Specific nAb for Unvaccinated Participants Receiving the 2-Dose Regimen 28 days after Dose 1	18.6 AU/mL Interval 11.1 to 31.2	28.4 AU/mL Interval 15.2 to 53.1	58.2 AU/mL Interval 31.4 to 107.8	—
Part A: GMC of SARS-CoV-2-Specific nAb for Unvaccinated Participants Receiving the 2-Dose Regimen 28 days after Dose 2	54.2 AU/mL Interval 23.4 to 125.5	187.9 AU/mL Interval 67.6 to 522.6	1658.4 AU/mL Interval 951.1 to 2891.6	—
Part A: GMC of SARS-CoV-2-Specific nAb for Unvaccinated Participants Receiving the 2-Dose Regimen 6 months after Dose 2	859.0 AU/mL	4134.0 AU/mL	948.5 AU/mL Interval 322.7 to 2787.6	—
Part A: GMC of SARS-CoV-2-Specific nAb for Unvaccinated Participants Receiving the 2-Dose Regimen 1 year after Dose 2	412.0 AU/mL	7285.0 AU/mL	1439.3 AU/mL Interval 100.8 to 20561.0	—

SECONDARY outcome

Timeframe: 28 days after Dose 3, 6 months after Dose 3, and 1 year after Dose 3

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=52 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=24 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=76 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: GMC of SARS-CoV-2-Specific nAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen 28 days after Dose 3	353.5 AU/mL Interval 171.2 to 729.7	1340.2 AU/mL Interval 617.4 to 2909.1	538.4 AU/mL Interval 307.2 to 943.7	—
Part A: GMC of SARS-CoV-2-Specific nAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen 6 months after Dose 3	222.5 AU/mL Interval 72.7 to 681.4	867.2 AU/mL Interval 62.9 to 11960.3	292.1 AU/mL Interval 109.1 to 782.0	—
Part A: GMC of SARS-CoV-2-Specific nAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen 1 year after Dose 3	990.7 AU/mL Interval 198.6 to 4942.3	480.8 AU/mL Interval to 4400000000000.0 Result below the LLOQ.	899.7 AU/mL Interval 217.0 to 3729.4	—

SECONDARY outcome

Timeframe: 28 days after Dose 1, 28 days after Dose 2, 6 months after Dose 2, and 1 year after Dose 2

The GMFR measures the changes in immunogenicity titers or levels from Baseline within participants. The GMFR of VAC62 antibodies, as measured by PsVNA specific to the SARS-CoV-2 spike protein is reported. Antibody values reported as below the LLOQ were replaced by 0.5\*LLOQ. Values that were greater than the ULOQ were replaced by the ULOQ if actual values were not available. LLOQ was 10 and ULOQ was 111433 AU/mL. The 95% CIs were calculated based on the t-distribution of the log-transformed values or the difference in the log-transformed values for GMC value, then back transformed to the original scale for presentation. Results in healthy participants were included as reference not for any comparisons. 95% CI cannot be calculated with an 'N' less than 2.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=23 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=14 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=16 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: GMFR of nAb for Unvaccinated Participants Receiving the 2-Dose Regimen Relative to Day 1 28 days after Dose 1	1.3 ratio Interval 0.8 to 2.1	2.1 ratio Interval 0.9 to 5.0	5.2 ratio Interval 2.7 to 9.9	—
Part A: GMFR of nAb for Unvaccinated Participants Receiving the 2-Dose Regimen Relative to Day 1 28 days after Dose 2	3.7 ratio Interval 1.7 to 8.2	13.8 ratio Interval 3.7 to 51.9	148.4 ratio Interval 84.3 to 261.2	—
Part A: GMFR of nAb for Unvaccinated Participants Receiving the 2-Dose Regimen Relative to Day 1 6 months after Dose 2	171.8 ratio	826.8 ratio	96.4 ratio Interval 36.8 to 252.8	—
Part A: GMFR of nAb for Unvaccinated Participants Receiving the 2-Dose Regimen Relative to Day 1 1 year after Dose 2	82.4 ratio	1457.0 ratio	145.1 ratio Interval 11.8 to 1778.7	—

SECONDARY outcome

Timeframe: 28 days after Dose 3, 6 months after Dose 3, 1 year after Dose 3

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=22 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=11 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=33 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: GMFR of nAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen Relative to Day 1 28 days after Dose 3	16.6 ratio Interval 6.6 to 41.7	56.8 ratio Interval 10.5 to 306.4	25.0 ratio Interval 11.2 to 55.9	—
Part A: GMFR of nAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen Relative to Day 1 6 months after Dose 3	16.2 ratio Interval 4.2 to 62.7	65.8 ratio Interval 3.0 to 1429.9	25.8 ratio Interval 7.7 to 86.7	—
Part A: GMFR of nAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen Relative to Day 1 1 year after Dose 3	990.7 ratio Interval 198.6 to 4942.3	480.8 ratio Interval to 4400000000000.0 Result below the LLOQ.	899.7 ratio Interval 217.0 to 3729.4	—

SECONDARY outcome

Timeframe: Days 1, 28 days after Dose 1, 28 days after Dose 2, 6 months after Dose 2, and 1 year after Dose 2

The GM level of VAC123 spike antibodies, as measured by MesoScale Discovery (MSD) electrochemiluminescence (ECL) multiplex assay specific to the SARS-CoV-2 spike protein is reported. Antibody values reported as below the LLOQ were replaced by 0.5\*LLOQ. Values that were greater than the ULOQ were replaced by the ULOQ if actual values were not available. LLOQ was 69 and ULOQ was 14400000 AU/mL. The 95% CIs were calculated based on the t-distribution of the log-transformed values or the difference in the log-transformed values for GM value, then back transformed to the original scale for presentation. Results in healthy participants were included as reference not for any comparisons. 95% CI cannot be calculated with an 'N' less than 2.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=24 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=14 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=16 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Geometric Mean (GM) Value of Anti-SARS-CoV-2 S-specific Binding Antibody (bAb) for Unvaccinated Participants Receiving the 2-Dose Regimen Day 1	68.3 AU/mL Interval 39.9 to 116.9	59.1 AU/mL Interval 33.6 to 104.0	53.6 AU/mL Interval 34.4 to 83.4	—
Part A: Geometric Mean (GM) Value of Anti-SARS-CoV-2 S-specific Binding Antibody (bAb) for Unvaccinated Participants Receiving the 2-Dose Regimen 28 days after Dose 1	346.4 AU/mL Interval 127.7 to 939.6	1213.9 AU/mL Interval 269.5 to 5467.4	23668.2 AU/mL Interval 13462.8 to 41609.8	—
Part A: Geometric Mean (GM) Value of Anti-SARS-CoV-2 S-specific Binding Antibody (bAb) for Unvaccinated Participants Receiving the 2-Dose Regimen 28 days after Dose 2	3190.1 AU/mL Interval 828.4 to 12284.7	20734.0 AU/mL Interval 3689.2 to 116527.2	272797.7 AU/mL Interval 188489.1 to 394816.2	—
Part A: Geometric Mean (GM) Value of Anti-SARS-CoV-2 S-specific Binding Antibody (bAb) for Unvaccinated Participants Receiving the 2-Dose Regimen 6 months after Dose 2	84460.0 AU/mL	202997.0 AU/mL	97534.9 AU/mL Interval 47881.0 to 198681.0	—
Part A: Geometric Mean (GM) Value of Anti-SARS-CoV-2 S-specific Binding Antibody (bAb) for Unvaccinated Participants Receiving the 2-Dose Regimen 1 year after Dose 2	44828.0 AU/mL	167863.0 AU/mL	161241.8 AU/mL Interval 19006.2 to 1367917.7	—

SECONDARY outcome

Timeframe: 28 days after Dose 3, 6 months after Dose 3, and 1 year after Dose 3

The GM level of VAC123 spike antibodies, as measured by MSD ECL multiplex assay specific to the SARS-CoV-2 spike protein is reported. Antibody values reported as below the LLOQ were replaced by 0.5\*LLOQ. Values that were greater than the ULOQ were replaced by the ULOQ if actual values were not available. LLOQ was 69 and ULOQ was 14400000 AU/mL. The 95% CIs were calculated based on the t-distribution of the log-transformed values or the difference in the log-transformed values for GM value, then back transformed to the original scale for presentation. Results in healthy participants were included as reference not for any comparisons.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=53 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=24 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=77 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: GM Value of Anti-SARS-CoV-2 S-specific bAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen 28 days after Dose 3	26674.0 AU/mL Interval 10865.9 to 65480.5	167141.1 AU/mL Interval 69651.7 to 401083.3	47260.9 AU/mL Interval 23657.2 to 94415.1	—
Part A: GM Value of Anti-SARS-CoV-2 S-specific bAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen 6 months after Dose 3	19289.6 AU/mL Interval 5878.6 to 63295.3	69076.5 AU/mL Interval 12838.6 to 371658.0	24895.7 AU/mL Interval 9274.4 to 66828.7	—
Part A: GM Value of Anti-SARS-CoV-2 S-specific bAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen 1 year after Dose 3	66847.7 AU/mL Interval 16994.7 to 262942.2	42266.8 AU/mL Interval to 664919284614.9 Result below the LLOQ.	62884.2 AU/mL Interval 18998.9 to 208139.7	—

SECONDARY outcome

Timeframe: 28 days after Dose 1, 28 days after Dose 2, 6 months after Dose 2, and 1 year after Dose 2

The GMFR measures the changes in immunogenicity titers or levels from Baseline within participants. The GMFR of VAC123 spike antibodies, as measured by MSD ECL multiplex assay specific to the SARS-CoV-2 spike protein is reported. Antibody values reported as below the LLOQ were replaced by 0.5\*LLOQ. Values that were greater than the ULOQ were replaced by the ULOQ if actual values were not available. LLOQ was 69 and ULOQ was 14400000 AU/mL. The 95% CIs were calculated based on the t-distribution of the log-transformed values or the difference in the log-transformed values for GMFR, then back transformed to the original scale for presentation. Results in healthy participants were included as reference not for any comparisons. 95% CI cannot be calculated with an 'N' less than 2.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=23 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=14 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=16 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Geometric Mean Fold-Rise (GMFR) of bAb for Unvaccinated Participants Receiving the 2-Dose Regimen Relative to Day 1 28 days after Dose 1	4.9 ratio Interval 1.8 to 13.4	20.5 ratio Interval 4.3 to 97.0	441.9 ratio Interval 244.5 to 798.5	—
Part A: Geometric Mean Fold-Rise (GMFR) of bAb for Unvaccinated Participants Receiving the 2-Dose Regimen Relative to Day 1 28 days after Dose 2	45.4 ratio Interval 10.7 to 191.8	399.0 ratio Interval 64.0 to 2488.0	5092.9 ratio Interval 3032.6 to 8553.1	—
Part A: Geometric Mean Fold-Rise (GMFR) of bAb for Unvaccinated Participants Receiving the 2-Dose Regimen Relative to Day 1 6 months after Dose 2	2448.1 ratio	5884.0 ratio	1710.0 ratio Interval 755.9 to 3868.5	—
Part A: Geometric Mean Fold-Rise (GMFR) of bAb for Unvaccinated Participants Receiving the 2-Dose Regimen Relative to Day 1 1 year after Dose 2	1299.4 ratio	4865.6 ratio	2567.2 ratio Interval 47.8 to 137952.8	—

SECONDARY outcome

Timeframe: 28 days after Dose 3, 6 months after Dose 3, 1 year after Dose 3

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=22 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=11 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=33 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: GMFR of bAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen Relative to Day 1 28 days after Dose 3	275.5 ratio Interval 60.9 to 1246.2	1556.2 ratio Interval 219.1 to 11051.0	490.7 ratio Interval 151.8 to 1586.4	—
Part A: GMFR of bAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen Relative to Day 1 6 months after Dose 3	554.9 ratio Interval 161.0 to 1912.2	824.1 ratio Interval 124.9 to 5436.5	633.1 ratio Interval 251.7 to 1592.5	—
Part A: GMFR of bAb for Unvaccinated and Previously Vaccinated Participants Receiving the 3-Dose Regimen Relative to Day 1 1 year after Dose 3	690.8 ratio Interval 71.7 to 6656.9	746.2 ratio Interval to 6400000000000.0 Result below the LLOQ. 6400000000000	701.5 ratio Interval 114.3 to 4305.5	—

SECONDARY outcome

Timeframe: 14 days after second and third injection

Population: The modified intent-to-treat (mITT) set (Part A) included all participants who received at least 1 dose of study drug, had no immunologic or virologic evidence of prior COVID-19 at baseline/pre-vaccination before the first dose of study drug.

Asymptomatic SARS-CoV-2 infection was identified by absence of COVID-19 symptoms and infections as detected by reverse transcriptase polymerase chain reaction (RT-PCR) central or local test or serology test as binding antibody (bAb) level against SARS-CoV-2 nucleocapsid protein negative (as measured by Roche Elecsys) at Day 1 that became positive (as measured by Roche Elecsys) post-baseline or positive RT-PCR (CLIA-certified central or local) laboratory post-baseline at scheduled or unscheduled/illness visits. A summary of SAEs and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=2 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=1 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=70 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) n=45 Participants Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Number of SOT Participants With Asymptomatic SARS-CoV-2 Infection	0 Participants	1 Participants	8 Participants	4 Participants

SECONDARY outcome

Timeframe: 14 days after second and third injection

Population: The mITT set (Part A) included all participants who received at least 1 dose of study drug, had no immunologic or virologic evidence of prior COVID-19 at baseline/pre-vaccination before the first dose of study drug.

Asymptomatic SARS-CoV-2 infection was identified by absence of COVID-19 symptoms and infections as detected by reverse transcriptase polymerase chain reaction (RT-PCR1) central or local test or serology test as bAb level against SARS-CoV-2 nucleocapsid protein negative (as measured by Roche Elecsys) at Day 1 that became positive (as measured by Roche Elecsys) post-baseline or positive RT-PCR (CLIA-certified central or local) laboratory post-baseline at scheduled or unscheduled/illness visits. A summary of SAEs and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=17 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Number of Healthy Participants With Asymptomatic SARS-CoV-2 Infection	4 Participants	—	—	—

SECONDARY outcome

Timeframe: 14 days after second and third injection

COVID-19 case was identified as a positive post-baseline RT-PCR (CLIA-certified central or local) laboratory for SARS-CoV-2, together with at least 2 systemic symptoms: fever (≥ 38 degree celsius \[°C\]/≥ 100.4 degree fahrenheit \[°F\]), chills, myalgia, headache, sore throat, new olfactory and taste disorder(s), or at least 1 of the following respiratory signs/symptoms: cough, shortness of breath or difficulty breathing, or clinical or radiographical evidence of pneumonia. A summary of SAEs and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=2 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=1 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=70 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) n=45 Participants Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Number of SOT Participants With the Occurrence of COVID-19	0 Participants	0 Participants	12 Participants	7 Participants

SECONDARY outcome

Timeframe: 14 days after second and third injection

COVID-19 case was identified as a positive post-baseline RT-PCR (CLIA-certified central or local) laboratory for SARS-CoV-2, together with at least 2 systemic symptoms: fever (≥ 38°C/≥ 100.4°F), chills, myalgia, headache, sore throat, new olfactory and taste disorder(s), or at least 1 of the following respiratory signs/symptoms: cough, shortness of breath or difficulty breathing, or clinical or radiographical evidence of pneumonia. A summary of SAEs and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section. A summary of SAEs and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=17 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Number of Healthy Participants With the Occurrence of COVID-19	2 Participants	—	—	—

SECONDARY outcome

Timeframe: 14 days after second and third injection

Severe COVID-19 case was identified as a COVID-19 case (RT-PCR \[CLIA-certified central or local\] laboratory) for SARS-CoV-2, together with any of the following: respiratory rate ≥30 per minute, heart rate ≥125 beats per minute, oxygen saturation(SpO2) ≤93% on room air at sea level, or partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FIO2) \<300 millimeters of mercury (mmHg); or respiratory failure or acute respiratory distress syndrome (ARDS), defined as needing high-flow oxygen, noninvasive or mechanical ventilation, or extracorporeal membrane oxygenation) or evidence of shock (systolic blood pressure \<90 mm Hg, diastolic BP \<60 mm Hg, or requiring vasopressors); or significant acute renal, hepatic, or neurologic dysfunction; OR admission to an intensive care unit or death. A summary of SAEs and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=2 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=1 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=70 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) n=45 Participants Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Number of SOT Participants With the Occurrence of Severe COVID-19	0 Participants	0 Participants	1 Participants	2 Participants

SECONDARY outcome

Timeframe: 14 days after second and third injection

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=17 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Part A: Number of Healthy Participants With the Occurrence of Severe COVID-19	0 Participants	—	—	—

SECONDARY outcome

Timeframe: Throughout the study period (up to Day 450)

Population: Safety set included all participants who received at least 1 dose of study drug in this study.

A summary of serious adverse events (SAEs) and all nonserious AEs ("Other") reported up to the end of the study (up to Day 419), regardless of causality, is located in the Reported "Adverse Events" section.

Outcome measures

Outcome measures
Measure	SOT Kidney Participants n=137 Participants Unvaccinated or previously vaccinated SOT kidney participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Liver Participants n=77 Participants Unvaccinated or previously vaccinated SOT liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	SOT Total n=214 Participants Unvaccinated or previously vaccinated SOT kidney and liver participants received up to 3 100-μg doses of mRNA-1273 vaccine in Part A and a single 100-μg BD of mRNA-1273 vaccine in Part B.	Part A (Primary Series): Cohort A2 and A3 (SOT Liver Participants) Unvaccinated or previously vaccinated SOT liver participants received 2 100-μg doses of mRNA-1273 vaccine by IM injection, 28 days apart (on Day 1 and Day 29). Participants also receive a third dose (100-μg) of mRNA-1273 vaccine on Day 85 (56 days after Dose 2).
Parts A and B: Number of SOT Participants Who Changed Immunosuppressant Therapy	52 Participants	37 Participants	89 Participants	—

Adverse Events

SOT Kidney Participants

Serious events: 28 serious events

Other events: 49 other events

Deaths: 4 deaths

SOT Liver Participants

Serious events: 17 serious events

Other events: 38 other events

Deaths: 0 deaths

SOT Total

Serious events: 45 serious events

Other events: 87 other events

Deaths: 4 deaths

Healthy Participants

Serious events: 1 serious events

Other events: 13 other events

Deaths: 0 deaths

Serious adverse events

Other adverse events

Additional Information

Moderna Clinical Trials Support Center

ModernaTX, Inc.

Phone: 1-877-777-7187

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place