A Phase 3 Study of Revaccination in Subsequent Pregnancies With Bivalent RSV Vaccine and Duration of Protection of a Single Dose

June 4, 2026 updated by: Pfizer

A Phase 3 Study to Investigate the Safety, Tolerability, and Immunogenicity of Revaccinating Pregnant Participants During Subsequent Pregnancies and Persistence of Immunity of a Single Dose of a Bivalent Respiratory Syncytial Virus (RSV) Vaccine.

This study aims to check how safe and well-tolerated a second dose of RSVpreF is when given during later pregnancies, and to see how long the immunity lasts from a single dose given during a previous pregnancy by examining the blood of nonpregnant participants who had the vaccine before.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This study will include pregnant participants and their unborn babies (Cohort 1 and Cohort 2) and non-pregnant participants (Cohort 3), as described below:

  • Cohort 1- Pregnant participants who had previously received RSVpreF as part of a Pfizer clinical trial and have antibody data available from that trial will get a second dose of RSVpreF.
  • Cohort 2- Pregnant participants who received the RSVpreF in a previous pregnancy, either through commercial means with Abrysvo® or as part of a Pfizer clinical trial, will be randomly chosen to get either one dose of the RSVpreF or one dose of a placebo. This applies to those who do not have antibody data available from the earlier trial.

For both groups of pregnant participants, the study will look at how safe and well-tolerated the vaccine is during pregnancy, as well as how the body responds to it.

Infants will be monitored for six months after birth to check safety and antibodies level.

• Cohort 3- Nonpregnant participants who received RSVpreF during a previous pregnancy as part of an earlier clinical trial will have blood samples taken to see how well their immune response has persisted over time. Participants will not receive any vaccine.

Study Type

Interventional

Enrollment (Estimated)

550

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Argentina
      • Buenos Aires, Argentina, 1044
        • Recruiting
        • Centro de investigación Clínica OSECAC - Sede Jonas Salk
      • Buenos Aires, Argentina, C1428BNF
        • Recruiting
        • Equipo Ciencia
      • Salta, Argentina, 4400
        • Recruiting
        • Hospital Público Materno Infantil
    • Buenos Aires
      • Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina, C1426ABP
        • Recruiting
        • Fundación Respirar
      • Mar del Plata, Buenos Aires, Argentina, 7600
        • Recruiting
        • Clinica Del Niño Y La Madre
    • Tucumán Province
      • San Miguel de Tucumán, Tucumán Province, Argentina, 4000
        • Recruiting
        • Clínica Mayo de Urgencias Médicas Cruz Blanca S.R.L
      • San Miguel de Tucumán, Tucumán Province, Argentina, 4000
        • Recruiting
        • Instituto de Maternidad y Ginecología Nuestra Señora de las Mercedes
  • South Africa
    • Free State
      • Bloemfontein, Free State, South Africa, 9301
        • Recruiting
        • Josha Research
    • Gauteng
      • Johannesburg, Gauteng, South Africa, 2001
        • Recruiting
        • Wits RHI
      • Johannesburg, Gauteng, South Africa, 1864
        • Recruiting
        • University of Witwatersrand (WITS) - Vaccines and Infectious Diseases Analytics (VIDA)
      • Pretoria, Gauteng, South Africa, 0152
        • Not yet recruiting
        • Setshaba Research Centre
      • Pretoria, Gauteng, South Africa, 0181
        • Recruiting
        • Into Research
    • Western Cape
      • Cape Town, Western Cape, South Africa, 7700
        • Recruiting
        • MRC Unit on Child And Adolescent Health
      • Cape Town, Western Cape, South Africa, 7500
        • Recruiting
        • Family Clinical Research Unit (Fam-Cru)
      • Cape Town, Western Cape, South Africa, 7700
        • Recruiting
        • University of Cape Town Lung Institute (Pty) Ltd
  • The Gambia
      • Banjul, The Gambia, POBox 273
        • Recruiting
        • Medical Research Council Unit
  • United States
    • Alabama
      • Birmingham, Alabama, United States, 35233
        • Recruiting
        • University of Alabama at Birmingham - School of Medicine
      • Birmingham, Alabama, United States, 35233
        • Recruiting
        • Children's of Alabama
      • Birmingham, Alabama, United States, 35233
        • Recruiting
        • Center for Research in Women's Health
      • Birmingham, Alabama, United States, 35233
        • Recruiting
        • University of Alabama at Birmingham Women & Infants Center
      • Mobile, Alabama, United States, 36604
        • Recruiting
        • USA Health Strada Patient Care Center
      • Mobile, Alabama, United States, 36604
        • Recruiting
        • USA Health Children's and Women's Hospital
    • California
      • Los Angeles, California, United States, 90095
        • Recruiting
        • UCLA
      • Los Angeles, California, United States, 90095
        • Recruiting
        • Ronald Reagan UCLA Medical Center
      • Los Angeles, California, United States, 90024
        • Recruiting
        • Ronald Reagan UCLA Medical Center
      • Los Angeles, California, United States, 90095
        • Recruiting
        • UCLA (Outpatient Clinic)
      • Los Angeles, California, United States, 90095
        • Recruiting
        • Ronald Reagan UCLA Medical Center (inpatient hospital)
      • Los Angeles, California, United States, 90095
        • Recruiting
        • UCLA Clinical and Translational Research Center (research clinic)
      • Palo Alto, California, United States, 94304
        • Recruiting
        • Stanford University
      • Palo Alto, California, United States, 94304
        • Recruiting
        • Stanford University Medical Center
      • Palo Alto, California, United States, 94304
        • Recruiting
        • Lucile Packard Children's Hospital-Labor and Delivery Unit
      • Palo Alto, California, United States, 94304
        • Recruiting
        • Stanford Obstetrics Clinic
    • Colorado
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • Children's Hospital Colorado
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • Anschutz Health Sciences Building (AHSB)
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • CU Research Pharmacy
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • University of Colorado AO1 UCH
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • University of Colorado Hospital Inpatient Pavilion
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • University of Colorado Hospital Outpatient Pavilion
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • University of Colorado Research II Building
    • Florida
      • North Miami Beach, Florida, United States, 33162
        • Recruiting
        • Citadelle Clinical Research
      • Panama City, Florida, United States, 32405
        • Recruiting
        • Emerald Coast OBGYN Clinical Research
      • Panama City, Florida, United States, 32405
        • Recruiting
        • Emerald Coast Pediatrics
      • Panama City, Florida, United States, 32405
        • Recruiting
        • HCA Florida Gulf Coast Hospital
    • Idaho
      • Boise, Idaho, United States, 83706
        • Recruiting
        • Saint Alphonsus Regional Medical Center
      • Boise, Idaho, United States, 83712
        • Recruiting
        • St. Luke's Boise Medical Center
      • Boise, Idaho, United States, 83702
        • Recruiting
        • Advanced Specialty Research
      • Idaho Falls, Idaho, United States, 83404
        • Recruiting
        • Clinical Research Prime
      • Nampa, Idaho, United States, 83687
        • Recruiting
        • Saint Alphonsus Medical Center
      • Nampa, Idaho, United States, 83687
        • Recruiting
        • St. Luke's Nampa Medical Center
    • Iowa
      • Ames, Iowa, United States, 50010
        • Recruiting
        • Mary Greeley Medical Center
      • Ames, Iowa, United States, 50010
        • Recruiting
        • McFarland Clinic, PC
      • Ames, Iowa, United States, 50010
        • Recruiting
        • Accellacare - McFarland
    • Kansas
      • Kansas City, Kansas, United States, 66160
        • Recruiting
        • University of Kansas Medical Center
    • Louisiana
      • Lafayette, Louisiana, United States, 70508
        • Recruiting
        • Velocity Clinical Research, Lafayette
      • New Orleans, Louisiana, United States, 70119
        • Recruiting
        • Velocity Clinical Research - New Orleans
    • Massachusetts
      • Boston, Massachusetts, United States, 02118
        • Recruiting
        • Boston Medical Center
    • Mississippi
      • Gulfport, Mississippi, United States, 39503
        • Recruiting
        • Velocity Clinical Research, Gulfport
    • Montana
      • Great Falls, Montana, United States, 59405
        • Recruiting
        • Boeson Research GTF
      • Great Falls, Montana, United States, 59405
        • Recruiting
        • OBGYN Associates
      • Kalispell, Montana, United States, 59901
        • Recruiting
        • Boeson Research KAL
      • Kalispell, Montana, United States, 59901
        • Recruiting
        • Heart & Hands Midwifery
      • Missoula, Montana, United States, 59804
        • Recruiting
        • Boeson Research MSO
      • Missoula, Montana, United States, 59804
        • Recruiting
        • Origin Health
      • Missoula, Montana, United States, 59804
        • Recruiting
        • Boeson Research Laboratory
    • Nebraska
      • Grand Island, Nebraska, United States, 68803
        • Recruiting
        • Velocity Clinical Research, Grand Island
      • Norfolk, Nebraska, United States, 68701
        • Recruiting
        • Velocity Clinical Research, Norfolk
    • New Mexico
      • Albuquerque, New Mexico, United States, 87109
        • Recruiting
        • Lovelace Women's Hospital
      • Albuquerque, New Mexico, United States, 87107
        • Recruiting
        • Velocity Clinical Research, Albuquerque
      • Albuquerque, New Mexico, United States, 87107
        • Recruiting
        • Presbyterian Hospital
      • Albuquerque, New Mexico, United States, 87107
        • Recruiting
        • UNM Hospital
    • North Carolina
      • Durham, North Carolina, United States, 27710
        • Recruiting
        • Duke University - Main Hospital and Clinics
      • Durham, North Carolina, United States, 27705
        • Recruiting
        • Duke University - Main Hospital and Clinics
    • Ohio
      • Cincinnati, Ohio, United States, 45229
        • Recruiting
        • Cincinnati Children's Hospital Medical Center
    • South Carolina
      • Greenville, South Carolina, United States, 29605
        • Recruiting
        • Prisma Health
      • Greenville, South Carolina, United States, 29605
        • Recruiting
        • Prisma Health-Upstate
    • Texas
      • Houston, Texas, United States, 77024
        • Recruiting
        • Memorial Hermann Memorial City Hospital
      • Houston, Texas, United States, 77204
        • Recruiting
        • The University of Texas Health Science Center at Houston
      • Weatherford, Texas, United States, 76086
        • Recruiting
        • Medical City Weatherford
      • Weatherford, Texas, United States, 76086
        • Recruiting
        • Helios Clinical Research - WEA
      • Weatherford, Texas, United States, 76086
        • Recruiting
        • Weatherford OB/GYN Associates
    • Utah
      • Salt Lake City, Utah, United States, 84132
        • Recruiting
        • University of Utah
      • Salt Lake City, Utah, United States, 84112
        • Recruiting
        • University of Utah
      • Salt Lake City, Utah, United States, 84132
        • Recruiting
        • University of Utah Hospital
      • Salt Lake City, Utah, United States, 84132
        • Recruiting
        • University of Utah Clinical Neuroscience Center
      • Salt Lake City, Utah, United States, 84108
        • Recruiting
        • University of Utah Obstetrics and Gynecology Research Offices
      • Salt Lake City, Utah, United States, 84112
        • Recruiting
        • University of Utah Madsen Health Center - Women's Health
    • Virginia
      • Norfolk, Virginia, United States, 23502
        • Recruiting
        • Sentara Leigh Hospital
      • Norfolk, Virginia, United States, 23502
        • Recruiting
        • The Group For Women - Kempsville Office
      • Norfolk, Virginia, United States, 23502
        • Recruiting
        • Tidewater Physicians for Women
      • Norfolk, Virginia, United States, 23502
        • Recruiting
        • WomensCare Center
      • North Chesterfield, Virginia, United States, 23235
        • Recruiting
        • Virginia Physicians For Women (VPFW)
      • Richmond, Virginia, United States, 23226
        • Recruiting
        • Clinical Research Partners, LLC
      • Richmond, Virginia, United States, 23226
        • Recruiting
        • Infusion Solutions, LLC
    • Washington
      • Seattle, Washington, United States, 98105
        • Recruiting
        • Seattle Children's Hospital
      • Seattle, Washington, United States, 98195
        • Recruiting
        • University of Washington Medical Center - Montlake
      • Seattle, Washington, United States, 98101
        • Recruiting
        • Seattle Children's Research Institute
      • Seattle, Washington, United States, 98133
        • Recruiting
        • University of Washington - Northwest

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Pregnant Participants-Cohort 1 and Cohort 2 Key Inclusion Criteria

  • Women aged 18 to 49 who are pregnant, between 24 and 36 weeks along, and expecting one baby without known risks for complications can participate.
  • Had the RSVpreF or Abrysvo vaccine during a previous pregnancy.
  • Had an ultrasound scan at 18 weeks or later during their current pregnancy, with no major fetal problems detected.
  • Based on their medical history, physical check-up, and the doctor's judgment, they are found suitable to join the study.
  • Agrees to let their baby take part in the study and gives their permission.
  • Able to sign a consent form, agreeing to follow the rules and conditions of the study.

Key Exclusion Criteria

  • Received any approved or experimental RSV vaccine since their previous pregnancy.
  • Has a pre-pregnancy body mass index (BMI) over 40 kg/m2.
  • History of a severe bad reaction to a vaccine or a serious allergic reaction (like anaphylaxis) to any ingredient in the study vaccine or a similar vaccine.
  • Current pregnancy problems or issues at the time of giving consent.
  • Previous pregnancy issues or problems at the time of giving consent.
  • Women who are breastfeeding at the time of enrollment

Infant Participants

  • Proof that the parent(s) or legal guardian(s) has signed and dated a consent form.
  • Parent(s) or legal guardian(s) must agree to attend scheduled visits and follow the study plan, including laboratory tests and other procedures.

Nonpregnant Participants-Cohort 3 Key Inclusion Criteria

  • Have already received one dose of the RSVpreF vaccine during their previous pregnancy as part of the Pfizer clinical trial, and the results from that time can be used for this study.
  • Able to sign a consent form, agreeing to follow the rules and requirements of the study.

Key Exclusion Criteria

  • Received any approved or experimental RSV vaccine after participating in the Pfizer clinical trial.
  • Taking part in other studies with new drugs within 28 days before giving consent or during the study period.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Placebo
Biological: Placebo
Single Dose
Experimental: RSVpreF
Biological: RSVpreF
Single Dose

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Percentage of pregnant participants reporting local reactions
Time Frame: From Day 1 Through at least Day 7 after Vaccination
Pain at the injection site, redness, and swelling
From Day 1 Through at least Day 7 after Vaccination
Percentage of pregnant participants reporting systemic events
Time Frame: From Day 1 Through at least Day 7 after Vaccination
Fever, fatigue, headache, vomiting, nausea, diarrhea, muscle pain, and joint pain
From Day 1 Through at least Day 7 after Vaccination
Percentage of pregnant participants reporting adverse events
Time Frame: From Day 1 through 4 weeks after vaccination
From Day 1 through 4 weeks after vaccination
Percentage of pregnant participants reporting serious adverse events
Time Frame: From Day 1 throughout the study
From Day 1 throughout the study
In infant participants born to pregnant participants receiving a second dose of the study intervention, the percentage of participants reporting adverse events.
Time Frame: From birth through 1 month of age
From birth through 1 month of age
In infant participants born to pregnant participants receiving a second dose of the study intervention, the percentage of participants reporting serious adverse events and newly diagnosed medical conditions.
Time Frame: From birth through 6 months of age.
From birth through 6 months of age.
Proportion of participants achieving neutralizing antibody to RSV A and RSV B at birth
Time Frame: At birth
At birth

Secondary Outcome Measures

Outcome Measure
Time Frame
Proportion of participants achieving neutralizing antibody to RSV A and RSV B at 3 months and 6 months
Time Frame: At 3 months and 6 months
At 3 months and 6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Pfizer

Investigators

  • Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 16, 2025

Primary Completion (Estimated)

February 24, 2028

Study Completion (Estimated)

February 24, 2028

Study Registration Dates

First Submitted

March 4, 2025

First Submitted That Met QC Criteria

March 4, 2025

First Posted (Actual)

March 10, 2025

Study Record Updates

Last Update Posted (Actual)

June 5, 2026

Last Update Submitted That Met QC Criteria

June 4, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • C3671059
  • C3671059-OPENLABEL; Marguerite (Other Identifier: Alias Study Number)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

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.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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