A Phase 3 Study of Revaccination in Subsequent Pregnancies With Bivalent RSV Vaccine and Duration of Protection of a Single Dose
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.
- RSV Infection
At a glance
- Phase
- Phase 3
- Study type
- Interventional
- Sponsor
- Pfizer
- Enrolment target
- 550
- Started
- 16 April 2025
- Main results due
- 24 February 2028
- Study sites
- 96
- Registry updated
- 24 September 2026
Can you take part?
- Aged 0 years and over.
- Open to any sex.
- Healthy volunteers can take part.
These are the headline rules only. Every study has a longer list, and whether you are eligible is decided by the research team at the site — never by this page.
Read the full eligibility criteria
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.
What this study is about
In the sponsor’s own words, from the registry.
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 sites(96)
Center for Research in Women's Health
Birmingham, Alabama, United States
Recruiting
Children's of Alabama
Birmingham, Alabama, United States
Recruiting
University of Alabama at Birmingham - School of Medicine
Birmingham, Alabama, United States
Recruiting
University of Alabama at Birmingham Women & Infants Center
Birmingham, Alabama, United States
Recruiting
USA Health Children's and Women's Hospital
Mobile, Alabama, United States
Recruiting
USA Health Strada Patient Care Center
Mobile, Alabama, United States
Recruiting
ClinMed, LLC
Phoenix, Arizona, United States
Recruiting
Ronald Reagan UCLA Medical Center
Los Angeles, California, United States
Recruiting
Ronald Reagan UCLA Medical Center (inpatient hospital)
Los Angeles, California, United States
Recruiting
Ronald Reagan UCLA Medical Center
Los Angeles, California, United States
Recruiting
UCLA (outpatient clinic)
Los Angeles, California, United States
Recruiting
UCLA Clinical and Translational Research Center (research clinic)
Los Angeles, California, United States
Recruiting
UCLA
Los Angeles, California, United States
Recruiting
Lucile Packard Children's Hospital-Labor and Delivery Unit
Palo Alto, California, United States
Recruiting
Stanford Obstetrics Clinic
Palo Alto, California, United States
Recruiting
Stanford University Medical Center
Palo Alto, California, United States
Recruiting
Stanford University
Palo Alto, California, United States
Recruiting
Anschutz Health Sciences Building (AHSB)
Aurora, Colorado, United States
Recruiting
Children's Hospital Colorado
Aurora, Colorado, United States
Recruiting
CU Research Pharmacy
Aurora, Colorado, United States
Recruiting
University of Colorado AO1 UCH
Aurora, Colorado, United States
Recruiting
University of Colorado Hospital Inpatient Pavilion
Aurora, Colorado, United States
Recruiting
University of Colorado Hospital Outpatient Pavilion
Aurora, Colorado, United States
Recruiting
University of Colorado Research II Building
Aurora, Colorado, United States
Recruiting
Citadelle Clinical Research
North Miami Beach, Florida, United States
Recruiting
Emerald Coast OBGYN Clinical Research
Panama City, Florida, United States
Recruiting
Emerald Coast Pediatrics
Panama City, Florida, United States
Recruiting
HCA Florida Gulf Coast Hospital
Panama City, Florida, United States
Recruiting
Advanced Specialty Research
Boise, Idaho, United States
Recruiting
Saint Alphonsus Regional Medical Center
Boise, Idaho, United States
Recruiting
St. Luke's Boise Medical Center
Boise, Idaho, United States
Recruiting
Clinical Research Prime
Idaho Falls, Idaho, United States
Recruiting
Saint Alphonsus Medical Center
Nampa, Idaho, United States
Recruiting
St. Luke's Nampa Medical Center
Nampa, Idaho, United States
Recruiting
Accellacare - McFarland
Ames, Iowa, United States
Recruiting
Mary Greeley Medical Center
Ames, Iowa, United States
Recruiting
McFarland Clinic, PC
Ames, Iowa, United States
Recruiting
University of Kansas Medical Center
Kansas City, Kansas, United States
Recruiting
Velocity Clinical Research - New Orleans
New Orleans, Louisiana, United States
Recruiting
Boston Medical Center
Boston, Massachusetts, United States
Recruiting
Velocity Clinical Research, Gulfport
Gulfport, Mississippi, United States
Recruiting
Boeson Research GTF
Great Falls, Montana, United States
Recruiting
OBGYN Associates
Great Falls, Montana, United States
Recruiting
Boeson Research KAL
Kalispell, Montana, United States
Recruiting
Heart & Hands Midwifery
Kalispell, Montana, United States
Recruiting
Boeson Research Laboratory
Missoula, Montana, United States
Recruiting
Boeson Research MSO
Missoula, Montana, United States
Recruiting
Origin Health
Missoula, Montana, United States
Recruiting
Velocity Clinical Research, Grand Island
Grand Island, Nebraska, United States
Recruiting
Velocity Clinical Research, Norfolk
Norfolk, Nebraska, United States
Recruiting
Presbyterian Hospital
Albuquerque, New Mexico, United States
Recruiting
UNM Hospital
Albuquerque, New Mexico, United States
Recruiting
Velocity Clinical Research, Albuquerque
Albuquerque, New Mexico, United States
Recruiting
Lovelace Women's Hospital
Albuquerque, New Mexico, United States
Recruiting
Duke University - Main Hospital and Clinics
Durham, North Carolina, United States
Recruiting
Duke University - Main Hospital and Clinics
Durham, North Carolina, United States
Recruiting
Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States
Recruiting
Prisma Health Maternal Fetal Medicine
Greenville, South Carolina, United States
Recruiting
Prisma Health OBGYN Center
Greenville, South Carolina, United States
Recruiting
Memorial Hermann Memorial City Hospital
Houston, Texas, United States
Recruiting
Showing 60 of 96 sites — filter to narrow it down. 96 of the 96 sites on this study are recruiting right now — a site can stop enrolling while the study as a whole is still open.
Source: ClinicalTrials.gov record NCT06866405. Trialion does not run this study, is not paid to refer anyone to it, and cannot enrol you. Eligibility is always decided by the research team at the site.
Not the right study?
Answer three questions and see the studies recruiting near you, in plain language.
Find a study for me