CompletedNCT04424316Updated Feb 11, 2025Results posted

A Trial to Evaluate the Efficacy and Safety of RSVpreF in Infants Born to Women Vaccinated During Pregnancy.

A Phase 3 interventional study of RSVpreF and Placebo in Respiratory Tract Infection, sponsored by Pfizer. Completed at 464 sites in 18 countries. Open to female participants aged 0 Years to 49 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-02-11.

Sponsored by Pfizer · Phase 3, Interventional, and Prevention

Phase: Phase 3
Study type: Interventional
Enrollment: 14,727
Allocation: Randomized
Ages: 0 Years to 49 Years
Sex: Female

Study summary

This randomized, double-blinded, placebo-controlled Phase 3 study is designed to evaluate the efficacy and safety of maternal immunization with RSVpreF against medically attended lower respiratory tract illness (MA-LRTI) in infants.

Read the detailed description

This is a Phase 3, multicenter, randomized, double-blinded, placebo-controlled study to assess the efficacy, safety, and immunogenicity of RSVpreF or placebo (1:1 randomization) in infants born to healthy women vaccinated during pregnancy, as well as the safety and immunogenicity in the pregnant women. This will be a global study which will span multiple RSV seasons.

Conditions studied

Respiratory Tract Infection

Browse trials for

Respiratory Tract Infections 1,031

Keywords

Respiratory Tract infection
RSV
Vaccine
Maternal

Who can participate

Ages eligible: 0 Years to 49 Years
Sexes eligible: Female
Accepts healthy volunteers: Yes

Eligibility criteria

Inclusion Criteria - Maternal Participants:

Healthy women ≤49 years of age who are between 24 0/7 and 36 0/7 weeks of gestation on the day of planned vaccination, with an uncomplicated, singleton pregnancy, who are at no known increased risk for complications.
Willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.
Receiving prenatal standard of care based on country requirements.
Had a fetal anomaly ultrasound examination performed at ≥18 weeks of pregnancy with no significant fetal abnormalities observed.
Determined by medical history, physical examination, and clinical judgment to be appropriate for inclusion in the study.
Documented negative HIV antibody test, syphilis test, and hepatitis B virus (HBV) surface antigen test during this pregnancy and prior to randomization (Visit 1).
Intention to deliver at a hospital or birthing facility where study procedures can be obtained.
Expected to be available for the duration of the study and can be contacted by telephone during study participation.
Participant is willing to give informed consent for her infant to participate in the study.
Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent document (ICD) and in this protocol OR If the maternal participant is illiterate, a thumbprinted informed consent must be obtained, which must be signed and dated by an impartial witness who was present throughout the entire informed consent process confirming that the maternal participant has been informed of all pertinent aspects of the study.

Inclusion Criteria -Infant Participants:

Evidence of a signed and dated ICD signed by the parent(s)/legal guardian(s) OR If the infant participant's maternal participant/parent(s)/legal guardian(s) is illiterate, a thumbprinted informed consent must have been obtained, which must have been signed and dated by an impartial witness who was present throughout the entire informed consent process confirming that the maternal participant/parent(s)/legal guardian(s) has been informed of all pertinent aspects of the study for herself (maternal participant) and her fetus/infant prior to taking part in the study.
Parent(s)/legal guardian(s) willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.

Exclusion Criteria - Maternal Participants:

Prepregnancy body mass index (BMI) of >40 kg/m2. If prepregnancy BMI is not available, the BMI at the time of the first obstetric visit during the current pregnancy may be used.
Bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection.
History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the investigational product or any related vaccine.
Current pregnancy resulting from in vitro fertilization.
Current pregnancy complications or abnormalities at the time of consent that will increase the risk associated with the participation in and completion of the study, including but not limited to the following:
- Preeclampsia, eclampsia, or uncontrolled gestational hypertension.
- Placental abnormality.
- Polyhydramnios or oligohydramnios.
- Significant bleeding or blood clotting disorder.
- Endocrine disorders, including untreated hyperthyroidism or untreated hypothyroidism. This also includes disorders of glucose intolerance (eg, diabetes mellitus type 1 or 2) antedating pregnancy or occurring during pregnancy if uncontrolled at the time of consent.
- Any signs of premature labor with the current pregnancy or having ongoing intervention (medical/surgical) in the current pregnancy to prevent preterm birth.
Prior pregnancy complications or abnormalities at the time of consent, based on the investigator's judgment, that will increase the risk associated with the participation in and completion of the study, including but not limited to the following:
- Prior preterm delivery ≤34 weeks' gestation.
- Prior stillbirth or neonatal death.
- Previous infant with a known genetic disorder or significant congenital anomaly.
Major illness of the maternal participant or conditions of the fetus that, in the investigator's judgment, will substantially increase the risk associated with the maternal or infant participant's participation in, and completion of, the study or could preclude the evaluation of the maternal participant's response (includes positive serologic testing for regional endemic conditions assessed during routine maternal care, as per local standards of care and obstetric recommendations).
Congenital or acquired immunodeficiency disorder, or rheumatologic disorder or other illness requiring chronic treatment with known immunosuppressant medications, including monoclonal antibodies, within the year prior to enrollment.
Other acute or chronic medical or psychiatric condition including recent (within the past year) or active suicidal ideation or behavior or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the participant inappropriate for entry into this study.
Participation in other studies involving investigational drug(s) within 28 days prior to consent and/or during study participation.
Receipt of monoclonal antibodies within the year prior to enrollment or the use of systemic corticosteroids for >14 days within 28 days prior to study enrollment. Permitted treatments include the receipt of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) monoclonal antibodies, prednisone doses of \<20 mg/day for ≤14 days and, inhaled/nebulized, intra-articular, intrabursal, or topical (skin or eyes) corticosteroids.
Current alcohol abuse or illicit drug use. Note: Marijuana use is not considered an exclusion criterion for the study when elicited in participant screening, though it may be considered illicit in some locales.
Receipt of blood or plasma products or immunoglobulin (Ig), from 60 days before investigational product administration, or planned receipt through delivery, with 1 exception, Rho(D) immune globulin (eg, RhoGAM), which can be given at any time.
Previous vaccination with any licensed or investigational RSV vaccine or planned. Note: Licensed COVID-19 vaccines or COVID-19 vaccines authorized for temporary or emergency use will not be prohibited during the course of this study.
Investigator site staff members directly involved in the conduct of the study and their family members, site staff members otherwise supervised by the investigator, or Pfizer employees, including their family members, directly involved in the conduct of the study.
Participants who are breastfeeding at the time of enrollment.

Exclusion Criteria -Infant Participants:

o Infant who is a direct descendant (eg, child or grandchild) of the study personnel.

Study design

Phase: Phase 3
Primary purpose: Prevention
Allocation: Randomized
Intervention model: Parallel assignment
Masking: Quadruple (Participant, Care provider, Investigator, Outcomes assessor)
Enrollment: 14,727 participants (actual)

Study arms

Experimental
RSVpreF vaccine
RSVpreF
Biological: RSVpreF
Placebo comparator
Placebo dose
Placebo
Biological: Placebo

Interventions

BiologicalRSVpreF
RSV vaccine (RSVpreF)
BiologicalPlacebo
Placebo

What researchers measure

Primary outcomes

Percentage of Infant Participants With Medically Attended Lower Respiratory Tract Illness (MA-LRTI) Cases Due to RSV Occurring Within 90 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. MA-LRTI case: infant with an MA-RTI visit with age related fast breathing (respiratory rate \[RR\] more than or equal to \[\>=\] 60 breaths per minute \[bpm\] for less than \[\<\] 2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or oxygen saturation (SpO2) \<95 percent (%) or chest wall indrawing and RSV positive test results by reverse transcription-polymerase chain reaction (RT-PCR) testing of midturbinate nasal swab samples.
Time frame: Within 90 days after birth
Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 120 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. MA-LRTI case: Infant with an MA-RTI visit with age related fast breathing (RR \>=60 bpm for \<2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or SpO2 \<95% or chest wall indrawing and RSV positive test results by RT-PCR testing of midturbinate nasal swab samples.
Time frame: Within 120 days after birth
Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 150 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. MA-LRTI case: Infant with an MA-RTI visit with age related fast breathing (RR \>=60 bpm for \<2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or SpO2 \<95% or chest wall indrawing and RSV positive test results by RT-PCR testing of midturbinate nasal swab samples.
Time frame: Within 150 days after birth
Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 180 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. MA-LRTI case: Infant with an MA-RTI visit with age related fast breathing (RR \>=60 bpm for \<2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or SpO2 \<95% or chest wall indrawing and RSV positive test results by RT-PCR testing of midturbinate nasal swab samples.
Time frame: Within 180 days after birth
Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 90 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. Severe MA-LRTI cases were a subset of MA-LRTI cases, and all severe MA-LRTI cases included MA-LRTI cases. Severe MA-LRTI case was an RSV positively adjudicated event which met the following defined criteria: an infant with an MA-RTI visit and aged associated fast breathing (RR \>=70 bpm for \<2 months of age \[\<60 days of age\], \>=60 bpm for \>=2 months to \<12 months of age, or \>=50 bpm for \>=12 months to 24 months of age) or SpO2 \<93% or high-flow nasal cannula or mechanical ventilation (i.e., invasive or non-invasive) or intensive care unit (ICU) admission for more than (\>) 4 hours or failure to respond/unconscious.
Time frame: Within 90 days after birth
Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 120 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. Severe MA-LRTI cases were a subset of MA-LRTI cases, and all severe MA-LRTI cases were included MA-LRTI cases. Severe MA-LRTI case was an RSV positively adjudicated event which met the following defined criteria: an infant with an MA-RTI visit and aged associated fast breathing (RR \>=70 bpm for \<2 months of age \[\<60 days of age\], \>=60 bpm for \>=2 months to \<12 months of age, or \>=50 bpm for \>=12 months to 24 months of age) or SpO2 \<93% or high-flow nasal cannula or mechanical ventilation (i.e., invasive or non-invasive) or ICU admission for \>4 hours or failure to respond/unconscious.
Time frame: Within 120 days after birth
Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 150 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. Severe MA-LRTI cases were a subset of MA-LRTI cases, and all severe MA-LRTI cases were included MA-LRTI cases. Severe MA-LRTI case was an RSV positively adjudicated event which met the following defined criteria: an infant with an MA-RTI visit and aged associated fast breathing (RR \>=70 bpm for \<2 months of age \[\<60 days of age\], \>=60 bpm for \>=2 months to \<12 months of age, or \>=50 bpm for \>=12 months to 24 months of age) or SpO2 \<93% or high-flow nasal cannula or mechanical ventilation (i.e., invasive or non-invasive) or ICU admission for \>4 hours or failure to respond/unconscious.
Time frame: Within 150 days after birth
Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 180 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. Severe MA-LRTI cases were a subset of MA-LRTI cases, and all severe MA-LRTI cases were included MA-LRTI cases. Severe MA-LRTI case was an RSV positively adjudicated event which met the following defined criteria: an infant with an MA-RTI visit and aged associated fast breathing (RR \>=70 bpm for \<2 months of age \[\<60 days of age\], \>=60 bpm for \>=2 months to \<12 months of age, or \>=50 bpm for \>=12 months to 24 months of age) or SpO2 \<93% or high-flow nasal cannula or mechanical ventilation (i.e., invasive or non-invasive) or ICU admission for \>4 hours or failure to respond/unconscious.
Time frame: Within 180 days after birth
Percentage of Infant Participants With Adverse Events of Special Interest (AESI) (Safety)
AESI are a subset of targeted medical events based on review of known pharmacology, toxicology findings, possible class effects, published literature, and signals arising from safety data assessments, and on population under study. AESIs were based on targeted medical events associated with pregnant maternal participants and their infants prior to/during delivery and at birth. For infant participants the following were considered as protocol defined AESIs: Preterm birth (born at \<37 weeks gestation); birth weight 1001-2500 grams; developmental delay; positive viral (polymerase chain reaction \[PCR\] or antigen-based) testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), when not reported during MA-RTI visit, were reported as SARS-CoV-2 test positive. Extremely preterm birth (\<28 weeks) and extremely low birth weight (=\<1000 grams \[g\]) were reported as serious AESIs.
Time frame: From birth to 24 months of age
Percentage of Infant Participants With Neonatal Deaths (Safety)
Neonatal death was defined as the death of a live-born infant that occurred within a month after birth.
Time frame: Within 1 Month after birth
Percentage of Infant Participants With Congenital Malformations/Anomalies (Safety)
Congenital malformations/ anomalies were defined as structural or functional anomalies that occurred during intrauterine life and could be identified prenatally, at birth or later in life.
Time frame: At birth
Percentage of Infant Participants With Other Neonatal Events (Safety)
Other Neonatal problem included dysmaturity, neonatal illness, hospitalization, drug therapies, and neonatal death.
Time frame: Within 1 Month after birth
Number of Infant Participants According to Appearance, Pulse, Grimace, Activity, and Respiration (APGAR) Score at 1 Minute After Birth (Safety)
APGAR was a fast evaluation technique used to evaluate a newborn baby's overall health. APGAR stands for (A) Appearance (skin coloration), (P) Pulse (heart rate), (G) Grimace (reflex response), (A) Activity (muscle tone) and (R) Respiration (breathing). Each component was given a score of 0, 1, or 2; after summing up scores for each component a total possible score was of 0 (worst condition) to 10 (best condition), where higher scores indicate better health. A score of 7 to 10 was good, 4 to \<7 was moderate, and \<4 was poor.
Time frame: 1 minute after birth
Number of Infant Participants According to APGAR Score at 5 Minutes After Birth (Safety)
APGAR was a fast evaluation technique used to evaluate a newborn baby's overall health. APGAR stands for (A) Appearance (skin coloration), (P) Pulse (heart rate), (G) Grimace (reflex response), (A) Activity (muscle tone) and (R) Respiration (breathing). Each component was given a score of 0, 1, or 2; after summing up scores for each component a total possible score was of 0 (worst condition) to 10 (best condition), where higher scores indicate better health. A score of 7 to 10 was good, 4 to \<7 was moderate, and \<4 was poor.
Time frame: 5 minutes after birth
Number of Infant Participants According to APGAR Score at 10 Minutes After Birth (Safety)
APGAR was a fast evaluation technique used to evaluate a newborn baby's overall health. APGAR stands for (A) Appearance (skin coloration), (P) Pulse (heart rate), (G) Grimace (reflex response), (A) Activity (muscle tone) and (R) Respiration (breathing). Each component was given a score of 0, 1, or 2; after summing up scores for each component a total possible score was of 0 (worst condition) to 10 (best condition), where higher scores indicate better health. A score of 7 to 10 was good, 4 to \<7 was moderate, and \<4 was poor.
Time frame: 10 minutes after birth
Percentage of Infant Participants With Adverse Events (AEs) From Birth to 1 Month of Age (Safety)
An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.
Time frame: From birth to 1 month of age
Percentage of Infant Participants With Serious Adverse Events (SAEs) and Newly Diagnosed Chronic Medical Conditions (NDCMCs) From Birth Through 6 Months of Age (Safety)
An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event. An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects.
Time frame: From birth to 6 months of age
Percentage of Infant Participants With SAEs and NDCMCs From Birth Through 12 Months of Age (Safety)
An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event. An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects.
Time frame: From birth to 12 months of age
Percentage of Infant Participants With SAEs and NDCMCs From Birth Through 24 Months of Age (Safety)
An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event. An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects.
Time frame: From birth to 24 months of age
Percentage of Maternal Participants With Prespecified Local Reactions Within 7 Days After Vaccination (Safety)
Local reactions included redness, swelling, and pain at injection site and were recorded in electronic diary (e-diary). Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit= 0.5 centimetre (cm). Redness and swelling were graded as mild (\>2.0 to 5.0 cm), moderate (\>5.0 to 10.0 cm), severe (\>10.0 cm) and grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (did not interfere with activity), moderate (interfered with activity), severe (prevented daily activity) and grade 4 (emergency room visit or hospitalization for the severe pain at the injection site). Grade 4 reactions were classified by the investigator or medically qualified person.
Time frame: From Day 1 to Day 7 after vaccination
Percentage of Maternal Participants With Prespecified Systemic Events Within 7 Days After Vaccination (Safety)
Systemic events included: fever, fatigue, headache, nausea, muscle pain, joint pain, vomiting and diarrhea and were recorded by participants in an e-diary. Fever was defined as an oral temperature \>=38.0 degree Celsius \[C\]) and classified as mild (38.0 to 38.4), moderate (38.5 to 38.9), severe (39.0 to 40.0) and grade 4 (\>40.0 degree C). Headache, nausea, fatigue, muscle pain and joint pain were graded as mild (did not interfere with activity), moderate (some interference with activity), severe (prevented daily activity). Vomiting: mild (1-2 times in 24 hours \[H\]), moderate (\>2 times in 24 H), severe (required intravenous \[IV\] hydration). Diarrhea: mild (2-3 loose stools in 24 H), moderate (4-5 loose stools in 24 H), severe (\>=6 in 24 H). For all systemic events except fever, Grade 4= emergency room visit or hospitalization. Grade 4 events were classified by investigator or medically qualified person.
Time frame: From Day 1 to Day 7 after vaccination
Percentage of Maternal Participants With AEs From the Time of Vaccination Through 1 Month After Vaccination (Safety)
An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention Only AEs collected by non-systematic assessment (i.e. excluding local reactions and systemic events) were included in this outcome measure.
Time frame: From vaccination on Day 1 up to 1 month after vaccination
Percentage of Maternal Participants With SAEs Throughout the Study Period (Safety)
An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event.
Time frame: From vaccination on Day 1 up to 6 months after delivery (maximum up to 10 months)

Secondary outcomes

Percentage of Infant Participants With Cases of Hospitalization Due to RSV Within 90, 120, 150, 180 and 360 Days After Birth (Efficacy)
Results are reported as confirmed by endpoint adjudication committee.
Time frame: Within 90, 120, 150, 180 and 360 days after birth
Percentage of Infant Participants With MA-LRTI Cases Due to Any Cause With Protocol Defined Criteria Occurring Within 90, 120, 150, 180 and 360 Days After Birth (Efficacy)
MA-LRTI cases due to any cause was defined as an infant with a MA-RTI visit with age related fast breathing (RR \>=60 bpm for \<2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or SpO2 \<95% or chest wall indrawing.
Time frame: Within 90, 120, 150, 180 and 360 days after birth
Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 210, 240, 270 and 360 Days After Birth (Efficacy)
Results are presented as confirmed by endpoint adjudication committee. MA-LRTI case: Infant with an MA-RTI visit with age related fast breathing (RR \>=60 bpm for \<2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or SpO2 \<95% or chest wall indrawing and RSV positive test results by RT-PCR testing of midturbinate nasal swab samples.
Time frame: Within 210, 240, 270 and 360 days after birth

Results

Posted Feb 11, 2025

Participant flow

Participant flow — Overall Study
Milestone	Maternal Participants: RSVpreF	Maternal Participants: Placebo	Infant Participants: RSVpreF	Infant Participants: Placebo
Started	3712	3708	3661	3646
Safety population	3698	3687	3659	3646
Completed	3516	3509	3318	3294
Not completed	196	199	343	352
Withdrew: Adverse event	0	1	0	0
Withdrew: Death	1	0	8	14
Withdrew: Lost to follow-up	93	88	224	211
Withdrew: No longer met eligibility criteria	1	0	0	0
Withdrew: Other	15	11	34	45
Withdrew: Physician decision	1	0	1	1
Withdrew: Protocol violation	0	1	0	0
Withdrew: Withdrawal by subject	71	77	0	0
Withdrew: Withdrawal by parent/guardian	0	0	74	81
Withdrew: Randomized but not vaccinated	13	21	0	0
Withdrew: Mother vaccinated but unblinded during study	1	0	2	0

Outcome measures

PrimaryPercentage of Infant Participants With Medically Attended Lower Respiratory Tract Illness (MA-LRTI) Cases Due to RSV Occurring Within 90 Days After Birth (Efficacy)

Results are presented as confirmed by endpoint adjudication committee. MA-LRTI case: infant with an MA-RTI visit with age related fast breathing (respiratory rate \[RR\] more than or equal to \[\>=\] 60 breaths per minute \[bpm\] for less than \[\<\] 2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or oxygen saturation (SpO2) \<95 percent (%) or chest wall indrawing and RSV positive test results by reverse transcription-polymerase chain reaction (RT-PCR) testing of midturbinate nasal swab samples.

Time frame:: Within 90 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With Medically Attended Lower Respiratory Tract Illness (MA-LRTI) Cases Due to RSV Occurring Within 90 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Medically Attended Lower Respiratory Tract Illness (MA-LRTI) Cases Due to RSV Occurring Within 90 Days After Birth (Efficacy)	0.7	1.7

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 57.6 · 95% CI 31.3 to 74.6

PrimaryPercentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 120 Days After Birth (Efficacy)

Results are presented as confirmed by endpoint adjudication committee. MA-LRTI case: Infant with an MA-RTI visit with age related fast breathing (RR \>=60 bpm for \<2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or SpO2 \<95% or chest wall indrawing and RSV positive test results by RT-PCR testing of midturbinate nasal swab samples.

Time frame:: Within 120 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 120 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 120 Days After Birth (Efficacy)	1.1	2.5

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 54.5 · 95% CI 33.2 to 69.5

PrimaryPercentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 150 Days After Birth (Efficacy)

Time frame:: Within 150 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 150 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 150 Days After Birth (Efficacy)	1.5	3.1

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 50.0 · 95% CI 30.3 to 64.5

PrimaryPercentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 180 Days After Birth (Efficacy)

Time frame:: Within 180 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 180 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 180 Days After Birth (Efficacy)	1.9	3.7

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 49.2 · 95% CI 31.4 to 62.8

PrimaryPercentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 90 Days After Birth (Efficacy)

Results are presented as confirmed by endpoint adjudication committee. Severe MA-LRTI cases were a subset of MA-LRTI cases, and all severe MA-LRTI cases included MA-LRTI cases. Severe MA-LRTI case was an RSV positively adjudicated event which met the following defined criteria: an infant with an MA-RTI visit and aged associated fast breathing (RR \>=70 bpm for \<2 months of age \[\<60 days of age\], \>=60 bpm for \>=2 months to \<12 months of age, or \>=50 bpm for \>=12 months to 24 months of age) or SpO2 \<93% or high-flow nasal cannula or mechanical ventilation (i.e., invasive or non-invasive) or intensive care unit (ICU) admission for more than (\>) 4 hours or failure to respond/unconscious.

Time frame:: Within 90 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 90 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 90 Days After Birth (Efficacy)	0.2	1.0

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 82.4 · 95% CI 57.5 to 93.9

PrimaryPercentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 120 Days After Birth (Efficacy)

Results are presented as confirmed by endpoint adjudication committee. Severe MA-LRTI cases were a subset of MA-LRTI cases, and all severe MA-LRTI cases were included MA-LRTI cases. Severe MA-LRTI case was an RSV positively adjudicated event which met the following defined criteria: an infant with an MA-RTI visit and aged associated fast breathing (RR \>=70 bpm for \<2 months of age \[\<60 days of age\], \>=60 bpm for \>=2 months to \<12 months of age, or \>=50 bpm for \>=12 months to 24 months of age) or SpO2 \<93% or high-flow nasal cannula or mechanical ventilation (i.e., invasive or non-invasive) or ICU admission for \>4 hours or failure to respond/unconscious.

Time frame:: Within 120 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 120 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 120 Days After Birth (Efficacy)	0.4	1.4

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 73.5 · 95% CI 50.3 to 86.8

PrimaryPercentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 150 Days After Birth (Efficacy)

Time frame:: Within 150 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 150 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 150 Days After Birth (Efficacy)	0.5	1.7

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 70.5 · 95% CI 49.4 to 83.6

PrimaryPercentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 180 Days After Birth (Efficacy)

Time frame:: Within 180 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 180 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Severe MA-LRTI Cases Due to RSV Occurring Within 180 Days After Birth (Efficacy)	0.6	2.0

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 70.0 · 95% CI 50.6 to 82.5

PrimaryPercentage of Infant Participants With Adverse Events of Special Interest (AESI) (Safety)

AESI are a subset of targeted medical events based on review of known pharmacology, toxicology findings, possible class effects, published literature, and signals arising from safety data assessments, and on population under study. AESIs were based on targeted medical events associated with pregnant maternal participants and their infants prior to/during delivery and at birth. For infant participants the following were considered as protocol defined AESIs: Preterm birth (born at \<37 weeks gestation); birth weight 1001-2500 grams; developmental delay; positive viral (polymerase chain reaction \[PCR\] or antigen-based) testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), when not reported during MA-RTI visit, were reported as SARS-CoV-2 test positive. Extremely preterm birth (\<28 weeks) and extremely low birth weight (=\<1000 grams \[g\]) were reported as serious AESIs.

Time frame:: From birth to 24 months of age
Reported as:: Number · Percentage of participants

Percentage of Infant Participants With Adverse Events of Special Interest (AESI) (Safety)
Percentage of participants	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Adverse Events of Special Interest (AESI) (Safety)	11.9 (10.8 to 13.0)	10.3 (9.3 to 11.3)

PrimaryPercentage of Infant Participants With Neonatal Deaths (Safety)

Neonatal death was defined as the death of a live-born infant that occurred within a month after birth.

Time frame:: Within 1 Month after birth
Reported as:: Number · Percentage of participants

Percentage of Infant Participants With Neonatal Deaths (Safety)
Percentage of participants	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Neonatal Deaths (Safety)	0.1 (0.0 to 0.2)	0.1 (0.0 to 0.3)

PrimaryPercentage of Infant Participants With Congenital Malformations/Anomalies (Safety)

Congenital malformations/ anomalies were defined as structural or functional anomalies that occurred during intrauterine life and could be identified prenatally, at birth or later in life.

Time frame:: At birth
Reported as:: Number · Percentage of participants

Percentage of Infant Participants With Congenital Malformations/Anomalies (Safety)
Percentage of participants	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Congenital Malformations/Anomalies (Safety)	5.6	6.7

PrimaryPercentage of Infant Participants With Other Neonatal Events (Safety)

Other Neonatal problem included dysmaturity, neonatal illness, hospitalization, drug therapies, and neonatal death.

Time frame:: Within 1 Month after birth
Reported as:: Number · Percentage of participants

Percentage of Infant Participants With Other Neonatal Events (Safety)
Percentage of participants	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Other Neonatal Events (Safety)	6.2	5.5

PrimaryNumber of Infant Participants According to Appearance, Pulse, Grimace, Activity, and Respiration (APGAR) Score at 1 Minute After Birth (Safety)

APGAR was a fast evaluation technique used to evaluate a newborn baby's overall health. APGAR stands for (A) Appearance (skin coloration), (P) Pulse (heart rate), (G) Grimace (reflex response), (A) Activity (muscle tone) and (R) Respiration (breathing). Each component was given a score of 0, 1, or 2; after summing up scores for each component a total possible score was of 0 (worst condition) to 10 (best condition), where higher scores indicate better health. A score of 7 to 10 was good, 4 to \<7 was moderate, and \<4 was poor.

Time frame:: 1 minute after birth
Reported as:: Count of participants · Participants

Number of Infant Participants According to Appearance, Pulse, Grimace, Activity, and Respiration (APGAR) Score at 1 Minute After Birth (Safety)
Participants	Infant Participants: RSVpreF	Infant Participants: Placebo
Score <4	49	44
Score 4 to <7	135	124
Score 7 to 10	3441	3438

PrimaryNumber of Infant Participants According to APGAR Score at 5 Minutes After Birth (Safety)

Time frame:: 5 minutes after birth
Reported as:: Count of participants · Participants

Number of Infant Participants According to APGAR Score at 5 Minutes After Birth (Safety)
Participants	Infant Participants: RSVpreF	Infant Participants: Placebo
Score <4	8	5
Score 4 to <7	29	27
Score 7 to 10	3581	3570

PrimaryNumber of Infant Participants According to APGAR Score at 10 Minutes After Birth (Safety)

Time frame:: 10 minutes after birth
Reported as:: Count of participants · Participants

Number of Infant Participants According to APGAR Score at 10 Minutes After Birth (Safety)
Participants	Infant Participants: RSVpreF	Infant Participants: Placebo
Score <4	0	0
Score 4 to <7	6	4
Score 7 to 10	993	995

PrimaryPercentage of Infant Participants With Adverse Events (AEs) From Birth to 1 Month of Age (Safety)

Time frame:: From birth to 1 month of age
Reported as:: Number · Percentage of participants

Percentage of Infant Participants With Adverse Events (AEs) From Birth to 1 Month of Age (Safety)
Percentage of participants	Infant Participants: RSVpreF	Infant Participants: Placebo
Percentage of Infant Participants With Adverse Events (AEs) From Birth to 1 Month of Age (Safety)	38.0 (36.4 to 39.6)	35.4 (33.9 to 37.0)

PrimaryPercentage of Infant Participants With Serious Adverse Events (SAEs) and Newly Diagnosed Chronic Medical Conditions (NDCMCs) From Birth Through 6 Months of Age (Safety)

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event. An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects.

Time frame:: From birth to 6 months of age
Reported as:: Number · Percentage of participants

Percentage of Infant Participants With Serious Adverse Events (SAEs) and Newly Diagnosed Chronic Medical Conditions (NDCMCs) From Birth Through 6 Months of Age (Safety)
Percentage of participants	Infant Participants: RSVpreF	Infant Participants: Placebo
SAE	16.7 (15.5 to 17.9)	16.4 (15.2 to 17.7)
NDCMC	1.3 (0.9 to 1.7)	1.6 (1.2 to 2.1)

PrimaryPercentage of Infant Participants With SAEs and NDCMCs From Birth Through 12 Months of Age (Safety)

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event. An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects.

Time frame:: From birth to 12 months of age
Reported as:: Number · Percentage of participants

Percentage of Infant Participants With SAEs and NDCMCs From Birth Through 12 Months of Age (Safety)
Percentage of participants	Infant Participants: RSVpreF	Infant Participants: Placebo
SAE	17.3 (16.1 to 18.6)	17.2 (15.9 to 18.5)
NDCMC	2.1 (1.7 to 2.6)	2.3 (1.9 to 2.9)

PrimaryPercentage of Infant Participants With SAEs and NDCMCs From Birth Through 24 Months of Age (Safety)

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event. An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects.

Time frame:: From birth to 24 months of age
Reported as:: Number · Percentage of participants

Percentage of Infant Participants With SAEs and NDCMCs From Birth Through 24 Months of Age (Safety)
Percentage of participants	Infant Participants: RSVpreF	Infant Participants: Placebo
SAE	19.0 (17.8 to 20.4)	18.9 (17.6 to 20.2)
NDCMC	3.9 (3.3 to 4.6)	4.5 (3.8 to 5.2)

PrimaryPercentage of Maternal Participants With Prespecified Local Reactions Within 7 Days After Vaccination (Safety)

Local reactions included redness, swelling, and pain at injection site and were recorded in electronic diary (e-diary). Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit= 0.5 centimetre (cm). Redness and swelling were graded as mild (\>2.0 to 5.0 cm), moderate (\>5.0 to 10.0 cm), severe (\>10.0 cm) and grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (did not interfere with activity), moderate (interfered with activity), severe (prevented daily activity) and grade 4 (emergency room visit or hospitalization for the severe pain at the injection site). Grade 4 reactions were classified by the investigator or medically qualified person.

Time frame:: From Day 1 to Day 7 after vaccination
Reported as:: Number · Percentage of participants

Percentage of Maternal Participants With Prespecified Local Reactions Within 7 Days After Vaccination (Safety)
Percentage of participants	Maternal Participants: RSVpreF	Maternal Participants: Placebo
Redness: Any	7.2 (6.4 to 8.1)	0.2 (0.1 to 0.4)
Redness: Mild	5.0 (4.3 to 5.7)	0.1 (0.0 to 0.3)
Redness: Moderate	2.1 (1.7 to 2.6)	0.1 (0.0 to 0.3)
Redness: Severe	0.1 (0.0 to 0.3)	0 (0.0 to 0.1)
Redness: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)
Swelling: Any	6.2 (5.4 to 7.0)	0.2 (0.1 to 0.4)
Swelling: Mild	4.1 (3.5 to 4.8)	0.1 (0.0 to 0.3)
Swelling: Moderate	2.0 (1.6 to 2.5)	0.1 (0.0 to 0.2)
Swelling: Severe	0.1 (0.0 to 0.2)	0 (0.0 to 0.1)
Swelling: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)
Pain at injection site: Any	40.7 (39.1 to 42.3)	10.2 (9.2 to 11.2)
Pain at injection site: Mild	36.1 (34.6 to 37.7)	9.3 (8.4 to 10.3)
Pain at injection site: Moderate	4.5 (3.8 to 5.2)	0.9 (0.6 to 1.2)
Pain at injection site: Severe	0.1 (0.0 to 0.3)	0 (0.0 to 0.1)
Pain at injection site: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)

PrimaryPercentage of Maternal Participants With Prespecified Systemic Events Within 7 Days After Vaccination (Safety)

Systemic events included: fever, fatigue, headache, nausea, muscle pain, joint pain, vomiting and diarrhea and were recorded by participants in an e-diary. Fever was defined as an oral temperature \>=38.0 degree Celsius \[C\]) and classified as mild (38.0 to 38.4), moderate (38.5 to 38.9), severe (39.0 to 40.0) and grade 4 (\>40.0 degree C). Headache, nausea, fatigue, muscle pain and joint pain were graded as mild (did not interfere with activity), moderate (some interference with activity), severe (prevented daily activity). Vomiting: mild (1-2 times in 24 hours \[H\]), moderate (\>2 times in 24 H), severe (required intravenous \[IV\] hydration). Diarrhea: mild (2-3 loose stools in 24 H), moderate (4-5 loose stools in 24 H), severe (\>=6 in 24 H). For all systemic events except fever, Grade 4= emergency room visit or hospitalization. Grade 4 events were classified by investigator or medically qualified person.

Time frame:: From Day 1 to Day 7 after vaccination
Reported as:: Number · Percentage of participants

Percentage of Maternal Participants With Prespecified Systemic Events Within 7 Days After Vaccination (Safety)
Percentage of participants	Maternal Participants: RSVpreF	Maternal Participants: Placebo
Fever: >=38.0 degree C	2.6 (2.1 to 3.1)	2.9 (2.4 to 3.5)
Fever: 38.0 to 38.4 degree C	1.7 (1.3 to 2.1)	1.5 (1.1 to 2.0)
Fever: 38.5 to 38.9 degree C	0.8 (0.5 to 1.1)	1.2 (0.8 to 1.6)
Fever: 39.0 to 40.0 degree C	0.1 (0.0 to 0.2)	0.1 (0.0 to 0.3)
Fever: >40.0 degree C	0.1 (0.0 to 0.2)	0.1 (0.0 to 0.3)
Fatigue: Any	46.1 (44.5 to 47.7)	43.8 (42.2 to 45.4)
Fatigue: Mild	23.5 (22.1 to 24.9)	22.7 (21.4 to 24.1)
Fatigue: Moderate	21.3 (20.0 to 22.7)	19.6 (18.4 to 21.0)
Fatigue: Severe	1.3 (1.0 to 1.8)	1.4 (1.1 to 1.9)
Fatigue: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)
Headache: Any	31.0 (29.5 to 32.5)	27.6 (26.2 to 29.1)
Headache: Mild	20.2 (18.9 to 21.5)	17.9 (16.7 to 19.2)
Headache: Moderate	10.4 (9.4 to 11.4)	9.4 (8.5 to 10.4)
Headache: Severe	0.4 (0.2 to 0.7)	0.4 (0.2 to 0.6)
Headache: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)
Nausea: Any	20.0 (18.7 to 21.3)	19.3 (18.0 to 20.6)
Nausea: Mild	14.4 (13.3 to 15.6)	13.9 (12.8 to 15.0)
Nausea: Moderate	5.4 (4.7 to 6.1)	5.2 (4.5 to 6.0)
Nausea: Severe	0.2 (0.1 to 0.4)	0.2 (0.1 to 0.4)
Nausea: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)
Muscle pain: Any	26.6 (25.1 to 28.0)	17.1 (15.9 to 18.4)
Muscle pain: Mild	17.6 (16.4 to 18.9)	10.0 (9.0 to 11.0)
Muscle pain: Moderate	8.6 (7.7 to 9.5)	6.8 (6.0 to 7.7)
Muscle pain: Severe	0.4 (0.2 to 0.6)	0.3 (0.2 to 0.6)
Muscle pain: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)
Joint pain: Any	11.6 (10.6 to 12.7)	10.5 (9.5 to 11.6)
Joint pain: Mild	6.5 (5.7 to 7.3)	6.0 (5.2 to 6.8)
Joint pain: Moderate	4.9 (4.2 to 5.7)	4.4 (3.8 to 5.2)
Joint pain: Severe	0.2 (0.1 to 0.4)	0.1 (0.0 to 0.2)
Joint pain: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)
Vomiting: Any	7.9 (7.0 to 8.8)	7.0 (6.2 to 7.8)
Vomiting: Mild	6.4 (5.6 to 7.2)	5.4 (4.7 to 6.1)
Vomiting: Moderate	1.3 (0.9 to 1.7)	1.5 (1.2 to 2.0)
Vomiting: Severe	0.2 (0.1 to 0.4)	0.1 (0.0 to 0.2)
Vomiting: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)
Diarrhea: Any	11.3 (10.3 to 12.3)	11.4 (10.4 to 12.5)
Diarrhea: Mild	9.1 (8.2 to 10.1)	9.4 (8.4 to 10.4)
Diarrhea: Moderate	2.0 (1.6 to 2.5)	1.9 (1.4 to 2.4)
Diarrhea: Severe	0.1 (0.0 to 0.3)	0.2 (0.1 to 0.4)
Diarrhea: Grade 4	0 (0.0 to 0.1)	0 (0.0 to 0.1)

PrimaryPercentage of Maternal Participants With AEs From the Time of Vaccination Through 1 Month After Vaccination (Safety)

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention Only AEs collected by non-systematic assessment (i.e. excluding local reactions and systemic events) were included in this outcome measure.

Time frame:: From vaccination on Day 1 up to 1 month after vaccination
Reported as:: Number · Percentage of participants

Percentage of Maternal Participants With AEs From the Time of Vaccination Through 1 Month After Vaccination (Safety)
Percentage of participants	Maternal Participants: RSVpreF	Maternal Participants: Placebo
Percentage of Maternal Participants With AEs From the Time of Vaccination Through 1 Month After Vaccination (Safety)	14.0 (12.9 to 15.1)	13.2 (12.2 to 14.4)

PrimaryPercentage of Maternal Participants With SAEs Throughout the Study Period (Safety)

Time frame:: From vaccination on Day 1 up to 6 months after delivery (maximum up to 10 months)
Reported as:: Number · Percentage of participants

Percentage of Maternal Participants With SAEs Throughout the Study Period (Safety)
Percentage of participants	Maternal Participants: RSVpreF	Maternal Participants: Placebo
Percentage of Maternal Participants With SAEs Throughout the Study Period (Safety)	16.6 (15.4 to 17.8)	15.8 (14.6 to 17.0)

SecondaryPercentage of Infant Participants With Cases of Hospitalization Due to RSV Within 90, 120, 150, 180 and 360 Days After Birth (Efficacy)

Results are reported as confirmed by endpoint adjudication committee.

Time frame:: Within 90, 120, 150, 180 and 360 days after birth
Reported as:: Number · %participants with hospitalization cases

Percentage of Infant Participants With Cases of Hospitalization Due to RSV Within 90, 120, 150, 180 and 360 Days After Birth (Efficacy)
%participants with hospitalization cases	Infant Participants: RSVpreF	Infant Participants: Placebo
90 days after birth	0.3	0.9
120 days after birth	0.4	1.1
150 days after birth	0.5	1.2
180 days after birth	0.6	1.3
360 days after birth	1.4	1.9

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 69.7 · 95% CI 37.1 to 86.7
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 61.5 · 95% CI 28.6 to 80.3
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 57.1 · 95% CI 23.9 to 76.8
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 55.3 · 95% CI 23.8 to 74.6
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 24.2 · 95% CI -11.1 to 48.6

SecondaryPercentage of Infant Participants With MA-LRTI Cases Due to Any Cause With Protocol Defined Criteria Occurring Within 90, 120, 150, 180 and 360 Days After Birth (Efficacy)

MA-LRTI cases due to any cause was defined as an infant with a MA-RTI visit with age related fast breathing (RR \>=60 bpm for \<2 months of age \[\<60 days of age\], \>=50 bpm for \>=2 months to \<12 months of age, or \>=40 bpm for \>=12 months to 24 months of age) or SpO2 \<95% or chest wall indrawing.

Time frame:: Within 90, 120, 150, 180 and 360 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With MA-LRTI Cases Due to Any Cause With Protocol Defined Criteria Occurring Within 90, 120, 150, 180 and 360 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
90 days after birth	5.6	6.2
120 days after birth	8.1	8.8
150 days after birth	10.3	11.3
180 days after birth	12.4	13.0
360 days after birth	17.5	18.4

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 9.5 · 95% CI -10.1 to 25.7
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 6.7 · 95% CI -9.8 to 20.7
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 7.7 · 95% CI -6.5 to 20.1
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 4.1 · 95% CI -9.5 to 16.0
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 4.6 · 95% CI -6.6 to 14.6

SecondaryPercentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 210, 240, 270 and 360 Days After Birth (Efficacy)

Time frame:: Within 210, 240, 270 and 360 days after birth
Reported as:: Number · % of participants with MA-LRTI cases

Percentage of Infant Participants With MA-LRTI Cases Due to RSV Occurring Within 210, 240, 270 and 360 Days After Birth (Efficacy)
% of participants with MA-LRTI cases	Infant Participants: RSVpreF	Infant Participants: Placebo
210 days after birth	2.3	4.0
240 days after birth	2.5	4.2
270 days after birth	2.8	4.4
360 days after birth	3.4	5.1

Statistical analysis

Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 43.8 · 95% CI 25.6 to 57.7
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 39.7 · 95% CI 21.3 to 54.1
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 35.0 · 95% CI 16.1 to 49.9
Infant Participants: RSVpreF vs Infant Participants: Placebo · Vaccine efficacy: 33.0 · 95% CI 15.2 to 47.1

Adverse events

Collected over Maternal participants: Local reactions and systemic events: From Day 1 to Day 7 after vaccination; SAEs: From vaccination on Day 1 up to 6 months after delivery (maximum up to 10 months); Non-SAEs: From vaccination on Day 1 up to 1 month after vaccination; Infant participants: SAEs: From birth up to 24 months of age; Non-SAEs: From birth up to 1 month after birth. Non-serious events are listed at a 1% frequency threshold.

Adverse event summary by group
Group	Deaths	Serious	Other
Maternal Participants: RSVpreF	1/3,698 (0%)	613/3,698 (16.6%)	2,755/3,698 (74.5%)
Maternal Participants: Placebo	0/3,687 (0%)	581/3,687 (15.8%)	2,339/3,687 (63.4%)
Infant Participants: RSVpreF	8/3,659 (0.2%)	697/3,659 (19%)	674/3,659 (18.4%)
Infant Participants: Placebo	14/3,646 (0.4%)	689/3,646 (18.9%)	598/3,646 (16.4%)

Most frequent serious events

Showing 10 of 695

Most frequent serious events
Event	Maternal Participants: RSVpreF	Maternal Participants: Placebo	Infant Participants: RSVpreF	Infant Participants: Placebo
Jaundice neonatalPregnancy, puerperium and perinatal conditions	0/3698	0/3687	77/3659	69/3646
Foetal distress syndromePregnancy, puerperium and perinatal conditions	67/3698	65/3687	1/3659	0/3646
Pre-eclampsiaPregnancy, puerperium and perinatal conditions	67/3698	53/3687	0/3659	0/3646
Hyperbilirubinaemia neonatalHepatobiliary disorders	0/3698	0/3687	51/3659	42/3646
Premature babyPregnancy, puerperium and perinatal conditions	0/3698	0/3687	49/3659	42/3646
Respiratory distressRespiratory, thoracic and mediastinal disorders	0/3698	0/3687	49/3659	46/3646
Atrial septal defectCongenital, familial and genetic disorders	0/3698	0/3687	37/3659	46/3646
Arrested labourPregnancy, puerperium and perinatal conditions	37/3698	43/3687	0/3659	0/3646
Gestational hypertensionPregnancy, puerperium and perinatal conditions	43/3698	41/3687	0/3659	0/3646
Nonreassuring foetal heart rate patternCardiac disorders	37/3698	30/3687	0/3659	0/3646

Most frequent other events

Showing 10 of 20

Most frequent other events
Event	Maternal Participants: RSVpreF	Maternal Participants: Placebo	Infant Participants: RSVpreF	Infant Participants: Placebo
Fatigue (FATIGUE)General disorders	1696/3678	1599/3651	0/3659	0/3646
Injection site pain (PAIN AT INJECTION SITE)General disorders	1496/3678	371/3651	0/3659	0/3646
Headache (HEADACHE)Nervous system disorders	1141/3678	1009/3651	0/3659	0/3646
Myalgia (MUSCLE PAIN)Musculoskeletal and connective tissue disorders	977/3678	626/3651	0/3659	0/3646
Nausea (NAUSEA)Gastrointestinal disorders	734/3678	705/3651	0/3659	0/3646
Arthralgia (JOINT PAIN)Musculoskeletal and connective tissue disorders	426/3678	384/3651	0/3659	0/3646
Diarrhoea (DIARRHEA)Gastrointestinal disorders	414/3678	416/3651	0/3569	0/3646
Vomiting (VOMITING)Gastrointestinal disorders	289/3678	254/3651	0/3659	0/3646
Erythema (REDNESS)Skin and subcutaneous tissue disorders	265/3678	8/3651	0/3659	0/3646
Swelling (SWELLING)General disorders	228/3678	8/3651	0/3659	0/3646

Baseline characteristics

Maternal safety population included all randomized maternal participants who received investigational product. Infant safety population included all infant participants who were born to vaccinated maternal participants.

Age, Categorical
Age, Categorical(Participants)	Maternal Participants: RSVpreF	Maternal Participants: Placebo	Infant Participants: RSVpreF	Infant Participants: Placebo	Total
<=18 years	9	9	3659	3646	7323
Between 18 and 65 years	3689	3678	0	0	7367
>=65 years	0	0	0	0	0

Sex: Female, Male
Sex: Female, Male(Participants)	Maternal Participants: RSVpreF	Maternal Participants: Placebo	Infant Participants: RSVpreF	Infant Participants: Placebo	Total
Female	3698	3687	1794	1815	10994
Male	0	0	1865	1831	3696

Ethnicity (NIH/OMB)
Ethnicity (NIH/OMB)(Participants)	Maternal Participants: RSVpreF	Maternal Participants: Placebo	Infant Participants: RSVpreF	Infant Participants: Placebo	Total
Hispanic or Latino	1063	1086	1079	1081	4309
Not Hispanic or Latino	2605	2568	2529	2519	10221
Unknown or Not Reported	30	33	51	46	160

Race (NIH/OMB)
Race (NIH/OMB)(Participants)	Maternal Participants: RSVpreF	Maternal Participants: Placebo	Infant Participants: RSVpreF	Infant Participants: Placebo	Total
American Indian or Alaska Native	38	37	42	36	153
Asian	456	464	446	456	1822
Native Hawaiian or Other Pacific Islander	9	12	13	11	45
Black or African American	720	725	706	706	2857
White	2397	2375	2340	2328	9440
More than one race	30	21	65	59	175
Unknown or Not Reported	48	53	47	50	198

Study locations

464 sites

Central Research Associates, Inc.
Birmingham, Alabama 35205, United States
Endocrinology and Internal Medicine Associates, PC
Birmingham, Alabama 35205, United States
OB/GYN Associates of Alabama, PC
Birmingham, Alabama 35205, United States
Sharp and Stone OB/GYN PC
Birmingham, Alabama 35205, United States
St Vincent's Hospital
Birmingham, Alabama 35205, United States
Children's of Alabama
Birmingham, Alabama 35233, United States
UAB Women & Infants Center - UAB Medicine
Birmingham, Alabama 35233, United States
University of Alabama at Birmingham/Center for Women's Reproductive Health
Birmingham, Alabama 35233, United States
Cullman Clinical Research, Inc
Cullman, Alabama 35058, United States
Cullman Primary Care, PC
Cullman, Alabama 35058, United States
Cullman Regional
Cullman, Alabama 35058, United States
University of South Alabama Children's and Women's Hospital
Mobile, Alabama 36604, United States
USA Health Strada Patient Care Center
Mobile, Alabama 36604, United States
Springhill Medical Center
Mobile, Alabama 36608, United States
Velocity Clinical Research, Gulfport
Mobile, Alabama 36608, United States
Velocity Clinical Research - Pheonix
Phoenix, Arizona 85006, United States
Valleywise Comprehensive Health Center Women's Clinic
Phoenix, Arizona 85008, United States
Valleywise Health Medical Center
Phoenix, Arizona 85008, United States
Mesquite Pediatrics
Tucson, Arizona 85712, United States
Watching Over Mothers and Babies
Tucson, Arizona 85712, United States
Banner University Medical Center
Tucson, Arizona 85724, United States
University of Arizona
Tucson, Arizona 85724, United States
Banner University Medical Center ( North Campus )
Tucson, Arizona 87519, United States
St. Bernards Medical Center
Jonesboro, Arkansas 72401, United States
St. Bernards OBGYN Associates
Jonesboro, Arkansas 72401, United States
The Children's Clinic of Jonesboro, P.A.
Jonesboro, Arkansas 72401, United States
The Children's Clinic of Jonesboro, PA
Jonesboro, Arkansas 72401, United States
Century Research Institute
Bellflower, California 90706, United States
Chowchilla Medical Center
Chowchilla, California 93610, United States
Loma Linda University Pediatric Clinic - Highland
Highland, California 92346, United States
Century Research Institute
Huntington Park, California 90255, United States
Matrix Clinical Research
Huntington Park, California 90255, United States
Chemidox Clinical Trials
Lancaster, California 93534, United States
Leonard S. Kurian, M.D., A Medical Corporation
Lancaster, California 93534, United States
Women & Infants Pavilion, Antelope Valley Hospital
Lancaster, California 93534, United States
Loma Linda University Adventist Health Sciences Center
Loma Linda, California 92354, United States
Loma Linda University Faculty Medical Clinics
Loma Linda, California 92354, United States
Loma Linda University Pediatric Clinics
Loma Linda, California 92354, United States
Loma Linda Unversity Children's Hospital
Loma Linda, California 92354, United States
Long Beach Clinical Trials
Long Beach, California 90806, United States
Long Beach Memorial Medical Center
Long Beach, California 90806, United States
St Mary Medical Center
Long Beach, California 90806, United States
Century Research Institute
Los Angeles, California 90006, United States
Matrix Clinical Research..
Los Angeles, California 90006, United States
East LA Doctors Hospital
Los Angeles, California 90023, United States
Hollywood Presbyterian Medical Center
Los Angeles, California 90027, United States
Century Research Institute
Los Angeles, California 90033, United States
White Memorial Medical Center
Los Angeles, California 90033, United States
Peter Morton Medical Building
Los Angeles, California 90095, United States
Ronald Reagan UCLA Medical Center Drug Information Center Dept
Los Angeles, California 90095, United States
Ronald Reagan University of California Los Angeles Medical Center
Los Angeles, California 90095, United States
UCLA David Geffen School of Medicine
Los Angeles, California 90095, United States
Affiliated Physician Practice
Madera, California 93637, United States
Charles E. Ugwu-Oju, M.D., F.A.C.O.G., Obstetrics & Gynecology
Madera, California 93637, United States
Madera Community Hospital
Madera, California 93637, United States
Madera Family Medical Group
Madera, California 93637, United States
Monterey Park Hospital
Monterey Park, California 91754, United States
Lucile Packard Children's Hospital
Palo Alto, California 94304, United States
Stanford University
Palo Alto, California 94304, United States
Fomat- Raymond Poliakin, MD.
Thousand Oaks, California 91360, United States
Carey Chronis, MD
Ventura, California 93003, United States
Children's Hospital Colorado
Aurora, Colorado 80045, United States
University of Colorado Anschutz Inpatient Pavilion 2
Aurora, Colorado 80045, United States
University of Colorado AO1
Aurora, Colorado 80045, United States
University of Colorado Hospital Inpatient Pavilion
Aurora, Colorado 80045, United States
University of Colorado Hospital Outpatient Pavilion
Aurora, Colorado 80045, United States
University of Colorado Hospital
Aurora, Colorado 80045, United States
University of Colorado Leprino Building
Aurora, Colorado 80045, United States
University of Colorado Research II Building
Aurora, Colorado 80045, United States
Delta Memorial Hospital
Delta, Colorado 81416, United States
Colorado Canyon's Hospital
Fruita, Colorado 81521, United States
Boeson Research
Grand Junction, Colorado 81501, United States
Dino-Peds
Grand Junction, Colorado 81501, United States
Women's Health Care of Western Colorado
Grand Junction, Colorado 81501, United States
Boeson Research
Grand Junction, Colorado 81505, United States
Community Hospital
Grand Junction, Colorado 81505, United States
SCL St. Mary's Medical Center
Grand Junction, Colorado 81505, United States
Montrose Memorial Hospital
Montrose, Colorado 81401, United States
Yale School Medicine Church Street Research Unit
New Haven, Connecticut 06519, United States
Emerson Clinical Research Institute
Washington, District of Columbia 20011, United States
Axcess Medical Research
Loxahatchee Groves, Florida 33470, United States
North Shore Medical Center
Miami, Florida 33150, United States
Citadelle Clinical Research
North Miami Beach, Florida 33162, United States
A1 Imaging of Aventura
North Miami Beach, Florida 33180, United States
Rainbow Pediatrics
Panama City Beach, Florida 32407, United States
Baldwin Pediatrics
Panama City, Florida 32405, United States
Emerald Coast Obstetrics and Gynecology
Panama City, Florida 32405, United States
Emerald Coast Pediatrics
Panama City, Florida 32405, United States
Gulf Coast Regional Medical Center
Panama City, Florida 32405, United States
Rainbow Pediatrics
Panama City, Florida 32405, United States
American Research Centers of Florida
Pembroke Pines, Florida 33027, United States
Emory University Hospital Midtown
Atlanta, Georgia 30308, United States
Emory Clinic
Atlanta, Georgia 30322, United States
Emory University Investigational Drug Service
Atlanta, Georgia 30322, United States
Emory University School of Medicine
Atlanta, Georgia 30322, United States
Piedmont Columbus Regional Midtown
Columbus, Georgia 31901, United States
Columbus Regional Research Institute
Columbus, Georgia 31904, United States
1st Choice Urgent Care & Family Medicine
Blackfoot, Idaho 83221, United States
Bingham Memorial Hospital
Blackfoot, Idaho 83221, United States
Elite Clinical Trials LLLP
Blackfoot, Idaho 83221, United States

Showing the first 100 of 464 sites across 18 countries.

References and documents

Publications

Ginsburg AS, Srikantiah P. Respiratory syncytial virus: promising progress against a leading cause of pneumonia. Lancet Glob Health. 2021 Dec;9(12):e1644-e1645. doi: 10.1016/S2214-109X(21)00455-1. Epub 2021 Nov 11. No abstract available. PubMed 34774184 ↗

Study documents

Study protocol · Aug 8, 2022
Statistical analysis plan · Sep 2, 2022

Documents are hosted by the registry — open the source record to download them.

Individual participant data

Plan to share: Yes — Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

Registry details

Key details

Study ID: NCT04424316
Lead sponsor: Pfizer
Responsible party: Sponsor
First posted: Jun 9, 2020
Start date: Jun 17, 2020
Primary completion: Oct 27, 2023
Completion: Oct 27, 2023
Results posted: Feb 11, 2025
Last update: Feb 11, 2025

Study contacts

Pfizer CT.gov Call Center

study director · Pfizer

Oversight

Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

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This study is completed, as verified in Jan 2025. You cannot join it, but the record below documents what was studied.

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A Trial to Evaluate the Efficacy and Safety of RSVpreF in Infants Born to Women Vaccinated During Pregnancy.

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