Trial Outcomes & Findings for A Study to Assess Safety, Tolerability and Immunogenicity of RSVpreF From Multidose Vials in Healthy Female Adults. (NCT NCT06473519)

Last Updated: 2025-09-25

Results Overview

GMTs and corresponding 2-sided 95% confidence intervals (CIs) were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on the Student t distribution).

Recruitment status

COMPLETED

Study phase

PHASE3

Target enrollment

453 participants

Primary outcome timeframe

Before vaccination on Day 1

Results posted on

2025-09-25

Participant Flow

Participants were randomized to receive respiratory syncytial virus stabilized prefusion F subunit vaccine (RSVpreF) either with the preservative formulated in a multiple dose vial (MDV) or without the preservative formulated in a single dose vial (SDV). Preservative used was 2-phenoxyethanol (2-PE).

Participant milestones

Participant milestones
Measure	RSVpreF (With Preservative, MDV) Participants were randomized to receive only a single 0.5 milliliter (mL) dose from MDV of RSVpreF (120 micrograms \[mcg\]), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Overall Study STARTED	224	229
Overall Study Vaccinated (on Day 1)	223	227
Overall Study COMPLETED	220	218
Overall Study NOT COMPLETED	4	11

Reasons for withdrawal

Reasons for withdrawal
Measure	RSVpreF (With Preservative, MDV) Participants were randomized to receive only a single 0.5 milliliter (mL) dose from MDV of RSVpreF (120 micrograms \[mcg\]), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Overall Study Lost to Follow-up	2	5
Overall Study Withdrawal by Subject	1	4
Overall Study Randomized but not vaccinated	1	2

Baseline Characteristics

A Study to Assess Safety, Tolerability and Immunogenicity of RSVpreF From Multidose Vials in Healthy Female Adults.

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	RSVpreF (With Preservative, MDV) n=223 Participants Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=227 Participants Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.	Total n=450 Participants Total of all reporting groups
Age, Continuous	33.8 Years STANDARD_DEVIATION 9.3 • n=5 Participants	34.4 Years STANDARD_DEVIATION 8.8 • n=7 Participants	34.1 Years STANDARD_DEVIATION 9.1 • n=5 Participants
Sex: Female, Male Female	223 Participants n=5 Participants	227 Participants n=7 Participants	450 Participants n=5 Participants
Sex: Female, Male Male	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	46 Participants n=5 Participants	54 Participants n=7 Participants	100 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	174 Participants n=5 Participants	168 Participants n=7 Participants	342 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	3 Participants n=5 Participants	5 Participants n=7 Participants	8 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	3 Participants n=7 Participants	3 Participants n=5 Participants
Race (NIH/OMB) Asian	3 Participants n=5 Participants	3 Participants n=7 Participants	6 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	1 Participants n=7 Participants	1 Participants n=5 Participants
Race (NIH/OMB) Black or African American	55 Participants n=5 Participants	63 Participants n=7 Participants	118 Participants n=5 Participants
Race (NIH/OMB) White	161 Participants n=5 Participants	152 Participants n=7 Participants	313 Participants n=5 Participants
Race (NIH/OMB) More than one race	2 Participants n=5 Participants	3 Participants n=7 Participants	5 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	2 Participants n=5 Participants	2 Participants n=7 Participants	4 Participants n=5 Participants

PRIMARY outcome

Timeframe: Before vaccination on Day 1

Population: Evaluable immunogenicity population (EIP): all eligible participants who received the study intervention to which they were randomized, had blood drawn for assay testing within the specified time frame (27 to 42 days after vaccination) for 1 month after vaccination, had at least 1 valid and determinate assay result at the 1-month follow-up visit, and had no major protocol violations. Here, "Number Analyzed" signifies participants evaluable for specified rows.

GMTs and corresponding 2-sided 95% confidence intervals (CIs) were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on the Student t distribution).

Outcome measures

Outcome measures
Measure	RSVpreF (With Preservative, MDV) n=218 Participants Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=216 Participants Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Geometric Mean Titer (GMT) of Serum Neutralizing Titers (NTs) for Respiratory Syncytial Virus Subgroup A (RSV A) and Respiratory Syncytial Virus Subgroup B (RSV B) Before Vaccination RSV A	2362 Titer Interval 2118.7 to 2634.0	2472 Titer Interval 2226.2 to 2744.8
Geometric Mean Titer (GMT) of Serum Neutralizing Titers (NTs) for Respiratory Syncytial Virus Subgroup A (RSV A) and Respiratory Syncytial Virus Subgroup B (RSV B) Before Vaccination RSV B	2926 Titer Interval 2637.1 to 3245.7	3172 Titer Interval 2866.2 to 3509.8

PRIMARY outcome

Timeframe: 1 month after Vaccination on Day 1

Population: EIP: all eligible participants who received the study intervention to which they were randomized, had blood drawn for assay testing within the specified time frame (27 to 42 days after vaccination) for 1 month after vaccination, had at least 1 valid and determinate assay result at the 1-month follow-up visit, and had no major protocol violations. Here, "Overall Number of Participants Analyzed" signifies number of participants evaluable for this outcome measure.

GMTs and corresponding 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on the Student t distribution). GMTs of NTs for RSV A and B were reported in the descriptive data section of this outcome measure. GMR each for RSV A and RSV B was calculated as ratio of NTs of RSVpreF (MDV) to RSVpreF (SDV) and was reported in the statistical analysis section of this outcome measure.

Outcome measures

Outcome measures
Measure	RSVpreF (With Preservative, MDV) n=218 Participants Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=215 Participants Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
GMT and Geometric Mean Ratio (GMR) of Serum NTs for RSV A and RSV B at 1 Month After Vaccination RSV A	33715 Titer Interval 30737.7 to 36981.4	35131 Titer Interval 31949.4 to 38630.0
GMT and Geometric Mean Ratio (GMR) of Serum NTs for RSV A and RSV B at 1 Month After Vaccination RSV B	41471 Titer Interval 37505.0 to 45856.0	45374 Titer Interval 40664.0 to 50628.8

PRIMARY outcome

Timeframe: Day 1 through Day 7 after Vaccination

Population: Safety population consisted of all randomized participants who received study intervention.

Local reactions included redness, swelling and pain at injection site, reported in the electronic diary (e-diary) and the participant-reported reactogenicity (PARREACT) case report form (CRF). Redness and swelling were measured and recorded in measuring device units, where 1 measuring device unit= 0.5 centimeter (cm) and graded as mild: \>2.0 to 5.0 cm, moderate: \>5.0 to 10.0 cm, severe: \>10.0 cm, Grade 4: necrosis (redness and swelling) or exfoliative dermatitis (redness). Pain at injection site was graded as mild: did not interfere with activity, moderate: interfered with activity, severe: prevented daily activity, Grade 4: emergency room visit or hospitalization for severe pain at injection site.

Outcome measures

Outcome measures
Measure	RSVpreF (With Preservative, MDV) n=223 Participants Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=227 Participants Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Redness: Any	9.4 Percentage of participants Interval 5.9 to 14.0	15.9 Percentage of participants Interval 11.4 to 21.3
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Redness: Mild	5.8 Percentage of participants Interval 3.1 to 9.8	9.3 Percentage of participants Interval 5.8 to 13.8
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Redness: Moderate	2.2 Percentage of participants Interval 0.7 to 5.2	6.2 Percentage of participants Interval 3.4 to 10.1
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Redness: Severe	1.3 Percentage of participants Interval 0.3 to 3.9	0.4 Percentage of participants Interval 0.0 to 2.4
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Redness: Grade 4	0 Percentage of participants Interval 0.0 to 1.6	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Swelling: Any	13.9 Percentage of participants Interval 9.6 to 19.1	14.1 Percentage of participants Interval 9.8 to 19.3
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Swelling: Mild	8.1 Percentage of participants Interval 4.9 to 12.5	8.8 Percentage of participants Interval 5.5 to 13.3
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Swelling: Moderate	4.9 Percentage of participants Interval 2.5 to 8.7	4.8 Percentage of participants Interval 2.4 to 8.5
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Swelling: Severe	0.9 Percentage of participants Interval 0.1 to 3.2	0.4 Percentage of participants Interval 0.0 to 2.4
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Swelling: Grade 4	0 Percentage of participants Interval 0.0 to 1.6	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Pain at injection site: Any	46.6 Percentage of participants Interval 39.9 to 53.4	52.9 Percentage of participants Interval 46.1 to 59.5
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Pain at injection site: Mild	37.2 Percentage of participants Interval 30.9 to 43.9	43.6 Percentage of participants Interval 37.1 to 50.3
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Pain at injection site: Moderate	9.4 Percentage of participants Interval 5.9 to 14.0	8.4 Percentage of participants Interval 5.1 to 12.8
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Pain at injection site: Severe	0 Percentage of participants Interval 0.0 to 1.6	0.9 Percentage of participants Interval 0.1 to 3.1
Percentage of Participants With Local Reactions Within 7 Days After Vaccination Pain at injection site: Grade 4	0 Percentage of participants Interval 0.0 to 1.6	0 Percentage of participants Interval 0.0 to 1.6

PRIMARY outcome

Timeframe: Day 1 through Day 7 after Vaccination

Population: Safety population consisted of all randomized participants who received study intervention.

Systemic events included fever, fatigue, headache, vomiting, nausea, diarrhea, muscle pain and joint pain, recorded in the e-diary and PARREACT CRF. Fever measured in degree Celsius and ranged: mild (38.0 - 38.4); moderate (38.5 - 38.9); severe (39.0 - 40.0); Grade 4: \>40.0. Fatigue, headache, nausea, muscle and joint pain graded as: mild (didn't interfere with activity); moderate (some interference with activity); severe (prevented daily routine activity); Grade 4 \[emergency room (ER) visit or hospitalization). Vomiting graded as: mild (1-2 times in 24 hours\[h\]); moderate (\>2 times in 24h); severe (required intravenous hydration); Grade 4 (ER visit or hospitalization). Diarrhea graded as: mild (2-3 loose stools in 24h); moderate (4-5 loose stools in 24h); severe (6 or more loose stools in 24h); Grade 4 (ER visit or hospitalization).

Outcome measures

Outcome measures
Measure	RSVpreF (With Preservative, MDV) n=223 Participants Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=227 Participants Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Joint Pain: Grade 4	0 Percentage of participants Interval 0.0 to 1.6	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Vomiting: Any	3.6 Percentage of participants Interval 1.6 to 7.0	2.2 Percentage of participants Interval 0.7 to 5.1
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Vomiting: Mild	3.1 Percentage of participants Interval 1.3 to 6.4	1.8 Percentage of participants Interval 0.5 to 4.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Vomiting: Moderate	0 Percentage of participants Interval 0.0 to 1.6	0.4 Percentage of participants Interval 0.0 to 2.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Vomiting: Severe	0 Percentage of participants Interval 0.0 to 1.6	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Vomiting: Grade 4	0.4 Percentage of participants Interval 0.0 to 2.5	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Diarrhea: Any	17.5 Percentage of participants Interval 12.8 to 23.2	18.1 Percentage of participants Interval 13.4 to 23.9
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Diarrhea: Mild	11.7 Percentage of participants Interval 7.8 to 16.7	15.0 Percentage of participants Interval 10.7 to 20.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Diarrhea: Moderate	4.9 Percentage of participants Interval 2.5 to 8.7	3.1 Percentage of participants Interval 1.3 to 6.3
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Diarrhea: Severe	0.4 Percentage of participants Interval 0.0 to 2.5	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Diarrhea: Grade 4	0.4 Percentage of participants Interval 0.0 to 2.5	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fever: Any	3.1 Percentage of participants Interval 1.3 to 6.4	1.8 Percentage of participants Interval 0.5 to 4.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fever: Mild	1.8 Percentage of participants Interval 0.5 to 4.6	0.9 Percentage of participants Interval 0.1 to 3.2
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fever: Moderate	0.4 Percentage of participants Interval 0.0 to 2.5	0.4 Percentage of participants Interval 0.0 to 2.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fever: Severe	0.9 Percentage of participants Interval 0.1 to 3.2	0.4 Percentage of participants Interval 0.0 to 2.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fever: Grade 4	0 Percentage of participants Interval 0.0 to 1.7	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fatigue: Any	47.5 Percentage of participants Interval 41.0 to 54.5	46.7 Percentage of participants Interval 40.4 to 53.9
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fatigue: Mild	20.6 Percentage of participants Interval 15.6 to 26.7	21.1 Percentage of participants Interval 16.2 to 27.3
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fatigue: Moderate	25.1 Percentage of participants Interval 19.7 to 31.5	24.7 Percentage of participants Interval 19.4 to 31.1
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fatigue: Severe	1.8 Percentage of participants Interval 0.5 to 4.5	0.9 Percentage of participants Interval 0.1 to 3.2
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Fatigue: Grade 4	0 Percentage of participants Interval 0.0 to 1.6	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Headache: Any	36.8 Percentage of participants Interval 30.6 to 43.7	39.2 Percentage of participants Interval 33.1 to 46.3
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Headache: Mild	22.4 Percentage of participants Interval 17.2 to 28.6	22.9 Percentage of participants Interval 17.8 to 29.2
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Headache: Moderate	13.5 Percentage of participants Interval 9.3 to 18.7	15.4 Percentage of participants Interval 11.1 to 21.0
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Headache: Severe	0.9 Percentage of participants Interval 0.1 to 3.2	0.4 Percentage of participants Interval 0.0 to 2.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Headache: Grade 4	0 Percentage of participants Interval 0.0 to 1.6	0.4 Percentage of participants Interval 0.0 to 2.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Nausea: Any	19.3 Percentage of participants Interval 14.4 to 25.2	15.4 Percentage of participants Interval 11.1 to 21.0
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Nausea: Mild	13.5 Percentage of participants Interval 9.3 to 18.7	11.0 Percentage of participants Interval 7.3 to 16.0
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Nausea: Moderate	4.9 Percentage of participants Interval 2.5 to 8.7	4.4 Percentage of participants Interval 2.2 to 8.0
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Nausea: Severe	0.4 Percentage of participants Interval 0.0 to 2.5	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Nausea: Grade 4	0.4 Percentage of participants Interval 0.0 to 2.5	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Muscle Pain: Any	38.6 Percentage of participants Interval 32.3 to 45.5	31.7 Percentage of participants Interval 26.0 to 38.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Muscle Pain: Mild	25.1 Percentage of participants Interval 19.7 to 31.5	19.4 Percentage of participants Interval 14.6 to 25.3
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Muscle Pain: Moderate	13.0 Percentage of participants Interval 8.9 to 18.2	12.3 Percentage of participants Interval 8.4 to 17.5
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Muscle Pain: Severe	0.4 Percentage of participants Interval 0.0 to 2.5	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Muscle Pain: Grade 4	0 Percentage of participants Interval 0.0 to 1.6	0 Percentage of participants Interval 0.0 to 1.6
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Joint Pain: Any	14.8 Percentage of participants Interval 10.5 to 20.2	19.4 Percentage of participants Interval 14.6 to 25.3
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Joint Pain: Mild	8.5 Percentage of participants Interval 5.2 to 13.0	11.9 Percentage of participants Interval 8.1 to 17.0
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Joint Pain: Moderate	6.3 Percentage of participants Interval 3.5 to 10.4	7.5 Percentage of participants Interval 4.5 to 11.8
Percentage of Participants With Systemic Events Within 7 Days After Vaccination Joint Pain: Severe	0 Percentage of participants Interval 0.0 to 1.6	0 Percentage of participants Interval 0.0 to 1.6

PRIMARY outcome

Timeframe: Within 1 Month after Vaccination

Population: Safety population consisted of all randomized participants who received study intervention.

An AE was defined as any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention were included in evaluation of this outcome measure. AEs included both serious AEs (SAEs) and all non-SAEs. Events collected by systematic assessment (local reactions and systemic events) were excluded from evaluation.

Outcome measures

Outcome measures
Measure	RSVpreF (With Preservative, MDV) n=223 Participants Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=227 Participants Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Percentage of Participants With Adverse Events (AEs) Within 1 Month After Vaccination	9.0 Percentage of participants Interval 5.6 to 13.5	8.4 Percentage of participants Interval 5.1 to 12.8

PRIMARY outcome

Timeframe: Within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months)

Population: Safety population consisted of all randomized participants who received study intervention.

An AEs was defined as any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention. An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria - resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect and other important medical events per protocol of the study. Events collected by systematic assessment (local reactions and systemic events) were excluded from evaluation.

Outcome measures

Outcome measures
Measure	RSVpreF (With Preservative, MDV) n=223 Participants Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=227 Participants Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Percentage of Participants With SAEs Throughout the Study	0.4 Percentage of participants Interval 0.0 to 2.5	0.9 Percentage of participants Interval 0.1 to 3.1

SECONDARY outcome

Timeframe: 1 Month after Vaccination

Population: EIP was analyzed. Here, "Overall Number of Participants Analyzed" = number of participants evaluable for this outcome measure and "Number Analyzed" = number of participants evaluable for specified rows.

Seroresponse was defined as achieving a \>=4-fold rise from baseline (before vaccination) if the baseline measurement was above the lower limit of quantification (LLOQ). If the baseline measurement was below the LLOQ, a postvaccination assay result \>=4\*LLOQ was considered a seroresponse.

Outcome measures

Outcome measures
Measure	RSVpreF (With Preservative, MDV) n=218 Participants Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=215 Participants Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Percentage of Participants Achieving Seroresponse for RSV A and RSV B of Serum NTs at 1 Month After Vaccination RSV A	91.7 Percentage of participants Interval 87.3 to 95.0	91.6 Percentage of participants Interval 87.0 to 94.9
Percentage of Participants Achieving Seroresponse for RSV A and RSV B of Serum NTs at 1 Month After Vaccination RSV B	96.8 Percentage of participants Interval 93.5 to 98.7	90.7 Percentage of participants Interval 86.0 to 94.2

Adverse Events

RSVpreF (With Preservative, MDV)

Serious events: 1 serious events

Other events: 169 other events

Deaths: 0 deaths

RSVpreF (Without Preservative, SDV)

Serious events: 2 serious events

Other events: 174 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	RSVpreF (With Preservative, MDV) n=223 participants at risk Participants were randomized to receive only a single 0.5 mL dose from MDV of RSVpreF (120 mcg), intramuscularly on Day 1.	RSVpreF (Without Preservative, SDV) n=227 participants at risk Participants were randomized to receive entire content from SDV of RSVpreF (120 mcg), intramuscularly on Day 1.
Immune system disorders Anaphylactic reaction	0.00% 0/223 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.	0.44% 1/227 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.
Infections and infestations Appendicitis	0.00% 0/223 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.	0.44% 1/227 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.
Injury, poisoning and procedural complications Ankle fracture	0.45% 1/223 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.	0.00% 0/227 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.
Injury, poisoning and procedural complications Rib fracture	0.45% 1/223 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.	0.00% 0/227 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.
Injury, poisoning and procedural complications Road traffic accident	0.45% 1/223 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.	0.00% 0/227 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.
Injury, poisoning and procedural complications Tibia fracture	0.45% 1/223 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.	0.00% 0/227 • Systematic assessment (local reactions and systemic events): Day 1 through Day 7 after Vaccination; Non-systematic assessment (serious AEs and all-cause mortality): within 42 to 49 days after Vaccination on Day 1 (maximum up to 1.6 months), Other AEs: within 1 month after Vaccination Same event may appear as both an AE and an SAE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. Safety population consisted of all randomized participants who received study intervention.

Other adverse events

Additional Information

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Results disclosure agreements

Principal investigator is a sponsor employee Pfizer has the right to review disclosures, requesting a delay of less than 60 days. Investigator will postpone single center publication until after disclosure of pooled data (all sites), less than 12 months from study completion/termination at all participating sites. Investigator may not disclose previously undisclosed confidential information other than study results.
Publication restrictions are in place

Restriction type: OTHER