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RSV InfectionPhase 3NCT06866405

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 testing RSVpreF in people with RSV Infection, run by Pfizer at 97 sites in 4 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

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. Read more about this study

Who is it for?
Ages 0 years and olderHealthy volunteers can take part
Conditions the study is for
RSV Infection
What is being tested?
RSVpreF
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
550 participants
Where
97 sitesin 4 countries
Study dates
16 Apr 2025to 24 Feb 2028
Phase
Phase 3
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 0 years and older
  • All sexes
  • Healthy volunteers accepted
  • Child, Adult, Older adult

Who may be able to join

None listed.

Who cannot join

  • 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
Show all 14Show fewer
  • 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.
  • 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.

Trial locations and contacts

97 sites in 4 countries. Contact the study team or a site near you to ask about taking part.

Pfizer CT.gov Call Center contact

1-800-718-1021

ClinicalTrials.gov_Inquiries@pfizer.com

97 sites in 4 countries

United States81 sites, 81 recruiting

  • Presbyterian Hospital

    Albuquerque, New Mexico, 87107

    Recruiting

  • UNM Hospital

    Albuquerque, New Mexico, 87107

    Recruiting

  • Velocity Clinical Research, Albuquerque

    Albuquerque, New Mexico, 87107

    Recruiting

  • Lovelace Women's Hospital

    Albuquerque, New Mexico, 87109

    Recruiting

  • Accellacare - McFarland

    Ames, Iowa, 50010

    Recruiting

  • Mary Greeley Medical Center

    Ames, Iowa, 50010

    Recruiting

  • McFarland Clinic, PC

    Ames, Iowa, 50010

    Recruiting

  • Anschutz Health Sciences Building (AHSB)

    Aurora, Colorado, 80045

    Recruiting

  • Children's Hospital Colorado

    Aurora, Colorado, 80045

    Recruiting

  • CU Research Pharmacy

    Aurora, Colorado, 80045

    Recruiting

  • University of Colorado AO1 UCH

    Aurora, Colorado, 80045

    Recruiting

  • University of Colorado Hospital Inpatient Pavilion

    Aurora, Colorado, 80045

    Recruiting

  • University of Colorado Hospital Outpatient Pavilion

    Aurora, Colorado, 80045

    Recruiting

  • University of Colorado Research II Building

    Aurora, Colorado, 80045

    Recruiting

  • Center for Research in Women's Health

    Birmingham, Alabama, 35233

    Recruiting

  • Children's of Alabama

    Birmingham, Alabama, 35233

    Recruiting

  • University of Alabama at Birmingham - School of Medicine

    Birmingham, Alabama, 35233

    Recruiting

  • University of Alabama at Birmingham Women & Infants Center

    Birmingham, Alabama, 35233

    Recruiting

  • Advanced Specialty Research

    Boise, Idaho, 83702

    Recruiting

  • Saint Alphonsus Regional Medical Center

    Boise, Idaho, 83706

    Recruiting

  • St. Luke's Boise Medical Center

    Boise, Idaho, 83712

    Recruiting

  • Boston Medical Center

    Boston, Massachusetts, 02118

    Recruiting

  • Cincinnati Children's Hospital Medical Center

    Cincinnati, Ohio, 45229

    Recruiting

  • Duke University - Main Hospital and Clinics

    Durham, North Carolina, 27705

    Recruiting

  • Duke University - Main Hospital and Clinics

    Durham, North Carolina, 27710

    Recruiting

  • Velocity Clinical Research, Grand Island

    Grand Island, Nebraska, 68803

    Recruiting

  • Boeson Research GTF

    Great Falls, Montana, 59405

    Recruiting

  • OBGYN Associates

    Great Falls, Montana, 59405

    Recruiting

  • Prisma Health Maternal Fetal Medicine

    Greenville, South Carolina, 29605

    Recruiting

  • Prisma Health OBGYN Center

    Greenville, South Carolina, 29605

    Recruiting

  • Velocity Clinical Research, Gulfport

    Gulfport, Mississippi, 39503

    Recruiting

  • Memorial Hermann Memorial City Hospital

    Houston, Texas, 77024

    Recruiting

  • The University of Texas Health Science Center at Houston

    Houston, Texas, 77204

    Recruiting

  • Clinical Research Prime

    Idaho Falls, Idaho, 83404

    Recruiting

  • Boeson Research KAL

    Kalispell, Montana, 59901

    Recruiting

  • Heart & Hands Midwifery

    Kalispell, Montana, 59901

    Recruiting

  • University of Kansas Medical Center

    Kansas City, Kansas, 66160

    Recruiting

  • Ronald Reagan UCLA Medical Center

    Los Angeles, California, 90024

    Recruiting

  • Ronald Reagan UCLA Medical Center (inpatient hospital)

    Los Angeles, California, 90095

    Recruiting

  • Ronald Reagan UCLA Medical Center

    Los Angeles, California, 90095

    Recruiting

  • UCLA (outpatient clinic)

    Los Angeles, California, 90095

    Recruiting

  • UCLA Clinical and Translational Research Center (research clinic)

    Los Angeles, California, 90095

    Recruiting

  • UCLA

    Los Angeles, California, 90095

    Recruiting

  • Boeson Research Laboratory

    Missoula, Montana, 59804

    Recruiting

  • Boeson Research MSO

    Missoula, Montana, 59804

    Recruiting

  • Origin Health

    Missoula, Montana, 59804

    Recruiting

  • USA Health Children's and Women's Hospital

    Mobile, Alabama, 36604

    Recruiting

  • USA Health Strada Patient Care Center

    Mobile, Alabama, 36604

    Recruiting

  • Saint Alphonsus Medical Center

    Nampa, Idaho, 83687

    Recruiting

  • St. Luke's Nampa Medical Center

    Nampa, Idaho, 83687

    Recruiting

  • Velocity Clinical Research - New Orleans

    New Orleans, Louisiana, 70119

    Recruiting

  • Weill Cornell Medicine-Cornell University/New York Presbyterian Hospital-Alexandra Cohen Hospital for Women and Newborns

    New York, New York, 10065

    Not yet recruiting

  • Velocity Clinical Research, Norfolk

    Norfolk, Nebraska, 68701

    Recruiting

  • Sentara Leigh Hospital

    Norfolk, Virginia, 23502

    Recruiting

  • The Group For Women - Kempsville Office

    Norfolk, Virginia, 23502

    Recruiting

  • Tidewater Physicians for Women

    Norfolk, Virginia, 23502

    Recruiting

  • WomensCare Center

    Norfolk, Virginia, 23502

    Recruiting

  • Virginia Physicians For Women (VPFW)

    North Chesterfield, Virginia, 23235

    Recruiting

  • Citadelle Clinical Research

    North Miami Beach, Florida, 33162

    Recruiting

  • Lucile Packard Children's Hospital-Labor and Delivery Unit

    Palo Alto, California, 94304

    Recruiting

  • Stanford Obstetrics Clinic

    Palo Alto, California, 94304

    Recruiting

  • Stanford University Medical Center

    Palo Alto, California, 94304

    Recruiting

  • Stanford University

    Palo Alto, California, 94304

    Recruiting

  • Emerald Coast OBGYN Clinical Research

    Panama City, Florida, 32405

    Recruiting

  • Emerald Coast Pediatrics

    Panama City, Florida, 32405

    Recruiting

  • HCA Florida Gulf Coast Hospital

    Panama City, Florida, 32405

    Recruiting

  • ClinMed, LLC

    Phoenix, Arizona, 85004

    Recruiting

  • Clinical Research Partners, LLC

    Richmond, Virginia, 23226

    Recruiting

  • Infusion Solutions, LLC

    Richmond, Virginia, 23226

    Recruiting

  • University of Utah Obstetrics and Gynecology Research Offices

    Salt Lake City, Utah, 84108

    Recruiting

  • University of Utah Madsen Health Center - Women's Health

    Salt Lake City, Utah, 84112

    Recruiting

  • University of Utah

    Salt Lake City, Utah, 84112

    Recruiting

  • University of Utah Clinical Neuroscience Center

    Salt Lake City, Utah, 84132

    Recruiting

  • University of Utah

    Salt Lake City, Utah, 84132

    Recruiting

  • Seattle Children's Research Institute

    Seattle, Washington, 98101

    Recruiting

  • Seattle Children's Hospital

    Seattle, Washington, 98105

    Recruiting

  • University of Washington - Northwest

    Seattle, Washington, 98133

    Recruiting

  • University of Washington Medical Center - Montlake

    Seattle, Washington, 98195

    Recruiting

  • Helios Clinical Research - WEA

    Weatherford, Texas, 76086

    Recruiting

  • Medical City Weatherford

    Weatherford, Texas, 76086

    Recruiting

  • Weatherford OB/GYN Associates

    Weatherford, Texas, 76086

    Recruiting

Other trials in United States

South Africa8 sites, 8 recruiting

  • Josha Research

    Bloemfontein, Free State, 9301

    Recruiting

  • Family Clinical Research Unit (Fam-Cru)

    Cape Town, Western Cape, 7500

    Recruiting

  • MRC Unit on Child And Adolescent Health

    Cape Town, Western Cape, 7700

    Recruiting

  • University of Cape Town Lung Institute (Pty) Ltd

    Cape Town, Western Cape, 7700

    Recruiting

  • University of Witwatersrand (WITS) - Vaccines and Infectious Diseases Analytics (VIDA)

    Johannesburg, Gauteng, 1864

    Recruiting

  • Wits RHI

    Johannesburg, Gauteng, 2001

    Recruiting

  • Setshaba Research Centre

    Pretoria, Gauteng, 0152

    Recruiting

  • Into Research

    Pretoria, Gauteng, 0181

    Recruiting

Other trials in South Africa

Argentina7 sites, 7 recruiting

  • Centro de investigación Clínica OSECAC - Sede Jonas Salk

    Buenos Aires, 1044

    Recruiting

  • Equipo Ciencia

    Buenos Aires, C1428BNF

    Recruiting

  • Fundación Respirar

    Ciudad Autónoma de Buenos Aires, Buenos Aires, C1426ABP

    Recruiting

  • Clinica Del Niño Y La Madre

    Mar del Plata, Buenos Aires, 7600

    Recruiting

  • Hospital Público Materno Infantil

    Salta, 4400

    Recruiting

  • Clínica Mayo de Urgencias Médicas Cruz Blanca S.R.L

    San Miguel de Tucumán, Tucumán Province, 4000

    Recruiting

  • Instituto de Maternidad y Ginecología Nuestra Señora de las Mercedes

    San Miguel de Tucumán, Tucumán Province, 4000

    Recruiting

Other trials in Argentina

The Gambia1 site, 1 recruiting

  • Medical Research Council Unit

    Banjul, Fajara, PO Box 273

    Recruiting

Other trials in The Gambia

About this study

Official title: 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.

Read the 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.
Conditions
RSV Infection
Being tested
RSVpreF, Placebo
Keywords
Pregnancy, RSV vaccine, RSV, Maternal immunization
Medical subject headings
Respiratory Syncytial Virus Infections

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • RSVpreFBiological

    Single Dose

  • PlaceboBiological

    Single Dose

Study groups in NCT06866405
Study groupRoleWhat they receive
RSVpreFExperimentalNot described
Receives: Biological: RSVpreF
PlaceboPlacebo comparatorNot described
Receives: Biological: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Percentage of pregnant participants reporting local reactions

    Pain at the injection site, redness, and swelling

    Measured: From Day 1 Through at least Day 7 after Vaccination

  2. Percentage of pregnant participants reporting systemic events

    Fever, fatigue, headache, vomiting, nausea, diarrhea, muscle pain, and joint pain

    Measured: From Day 1 Through at least Day 7 after Vaccination

  3. Percentage of pregnant participants reporting adverse events

    Measured: From Day 1 through 4 weeks after vaccination

  4. Percentage of pregnant participants reporting serious adverse events

    Measured: From Day 1 throughout the study

  5. In infant participants born to pregnant participants receiving a second dose of the study intervention, the percentage of participants reporting adverse events.

    Measured: From birth through 1 month of age

  6. 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.

    Measured: From birth through 6 months of age.

  7. Proportion of participants achieving neutralizing antibody to RSV A and RSV B at birth

    Measured: At birth

Secondary outcomes (1)

  1. Proportion of participants achieving neutralizing antibody to RSV A and RSV B at 3 months and 6 months

    Measured: At 3 months and 6 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted10 Mar 2025
  2. Study start16 Apr 2025
  3. Primary completion24 Feb 2028 (estimated)
  4. Study completion24 Feb 2028 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
550 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06866405
Sponsor's protocol ID
C3671059
Other IDs
C3671059-OPENLABEL; Marguerite
Status last verified
Oct 2026
First submitted
4 Mar 2025
Last updated
14 Oct 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
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.

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing RSVpreF in people with RSV Infection, run by Pfizer at 97 sites in 4 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 0 inclusion and 14 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 14 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 97 sites in United States, South Africa, Argentina, The Gambia. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Pfizer CT.gov Call Center (1-800-718-1021, ClinicalTrials.gov_Inquiries@pfizer.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Percentage of pregnant participants reporting local reactions (time frame: From Day 1 Through at least Day 7 after Vaccination). The study lists 7 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06866405.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Oct 2026.

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