Respiratory Syncytial Virus (RSV)Phase 3NCT07839871
Study to Learn About a Respiratory Syncytial Virus Vaccine in Children at High Risk of RSV Disease
A Phase 3 study testing RSVpreF in people with Respiratory Syncytial Virus (RSV), run by Pfizer at 20 sites in 4 countries.
Trial summary
The purpose of the study is to evaluate the safety, tolerability, and immunogenicity of RSVpreF in children 5 to <18 years of age at high risk for RSV disease, including those who are immunocompromised. Read more about this study
- Who is it for?
- Ages 5 to 17 yearsHealthy volunteers can take part
- Conditions the study is for
- Respiratory Syncytial Virus (RSV)
- What is being tested?
- RSVpreF
- Type of treatment
- Vaccines
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 920 participants
- Where
- 20 sitesin 4 countries
- Study dates
- 22 Sep 2026to 30 Mar 2031
- 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 5 to 17 years
- All sexes
- Healthy volunteers accepted
- Child
Who may be able to join
- Participants' age requirements for each study cohort at enrollment, respectively Cohort 1a (chronic medical conditions) 12 to <18 years of age Cohort 1b (chronic medical conditions) 5 to <12 years of age Cohort 2a (immunocompromising conditions) 12 to <18 years of age Cohort 2b (immunocompromising conditions) 5 to <12 years of age
- Participants depending on the study cohort requirements, will be considered by the investigator to be at high risk of LRTI-RSV based on the following disease characteristics and definitions:
- Chronic medical conditions:
- Cystic fibrosis
- Medically treated asthma
- Other chronic respiratory diseases and malformations of the lung
Show all 21Show fewer
- Trisomy 21 (Down syndrome)
- Neuromuscular disease
- Cerebral palsy
- Hemodynamically significant or symptomatic congenital heart disease
- Sickle cell disease
- Confirmed stable HIV disease defined as documented viral load <50 copies/mL and CD4 count >200 cells/mm3 within 6 months before enrollment, and on stable antiretroviral therapy for at least 6 months
- Immunocompromising conditions:
- Immunomodulatory therapy: Is on an active immunosuppressive (including cytotoxic) or immunomodulatory therapy at a stable dose. Patients taking steroids as monotherapy must be on a dose of at least 2 mg/kg/day or 20 mg/day or greater OR
- Primary immune deficiency: Has a diagnosed primary immunodeficiency disease OR
- Cellular therapy: Has received a bone marrow or stem cell transplant at least 6 months (180 days) prior to enrollment with adequate immune reconstitution for immunization in the investigator's opinion or has received chimeric antigen receptor T cell (CAR-T) therapy more than 90 days prior to enrollment OR
- Solid organ transplant: Has received a solid organ transplant at least 3 months prior and with no acute rejection episodes within 90 days prior to enrollment and is on ongoing immunosuppressive therapy OR
- End-stage renal disease: Has end-stage renal disease (ESRD) on hemodialysis (HD)
- Participants' weight must be:
- Cohort 1a: ≥30.0 kg at enrollment Cohort 1b: ≥14.5 kg at enrollment Cohort 2a : ≥30 kg at enrollment Cohort 2b: ≥14.5 kg at enrollment
- •The participant's parent(s)/legal guardian is capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the ICD and in the protocol. Depending on the age of the participant and according to local requirements, participants will also be asked to provide assent as appropriate (verbal or written)
Who cannot join
- Applicable to Cohort 1 (a and b) participants only: Immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination
- Applicable to Cohort 1 (a and b) participants only: Individuals with a history of autoimmune disease, past or present, requiring therapeutic intervention including, but not limited to, systemic lupus erythematosus. Note: Stable type 1 diabetes and hypothyroidism are permitted
- History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s)
- Bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection
- Individuals with epilepsy or other seizure disorders that is uncontrolled/unstable, or a history of seizures and/or other neurological complications following vaccination
- History of Guillain-Barré syndrome and/or acute polyneuropathy without an underlying etiology.
- Individuals who are pregnant
- Any medical or psychiatric condition, including any active suicidal ideation in the past year or suicidal behavior in the past 5 years or laboratory abnormality, that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study
Trial locations and contacts
20 sites in 4 countries. Contact the study team or a site near you to ask about taking part.
20 sites in 4 countries
Poland8 sites, 8 recruiting
- Not yet recruiting
Uniwersytecki Dziecięcy Szpital Kliniczny im. L. Zamenhofa w Białymstoku
Bialystok, 15-274
- Not yet recruiting
IN-VIVO Bydgoszcz
Bydgoszcz, 85-048
- Recruiting
Samodzielny Zespół Publiczny Zakładów Opieki Zdrowotnej im. Dzieci Warszawy w Dziekanowie Leśnym
Dziekanów Leśny, 05-092
- Not yet recruiting
Pro Familia Altera Sp. z o.o.
Katowice, 40-648
- Recruiting
Centrum Badań Klinicznych - Jagiellońskie Centrum Innowacji Sp. z o.o.
Krakow, 30-348
- Not yet recruiting
ZOZ Medyk Sp. z o.o.
Milówka, Silesian Voivodeship, 34-360
- Not yet recruiting
ALERGO-MED Osrodek Badan Klinicznych Sp z o.o.
Tarnów, 33-100
- Not yet recruiting
Szpital im.Sw.Jadwigi Slaskiej w Trzebnicy
Trzebnica, 55-100
United States5 sites, 5 recruiting
- Recruiting
Cincinnati Children's Hospital Medical Center Vaccine Research Center
Cincinnati, Ohio, 45206
- Recruiting
Duke Vaccine and Trials Unit
Durham, North Carolina, 27703
- Recruiting
Seattle Childrens Research Institute
Seattle, Washington, 98101
- Recruiting
Seattle Children's Hospital
Seattle, Washington, 98105
- Recruiting
Senders Pediatrics
South Euclid, Ohio, 44121
Spain4 sites, 4 recruiting
- Not yet recruiting
Servicio Andaluz de Salud (SAS) - Hospital de Antequera
Antequera, 29200
- Recruiting
Hospital Universitario La Paz
Madrid, Madrid, Comunidad de, 28046
- Not yet recruiting
Hospital Universitario HM Puerta del Sur
Móstoles, 28938
- Not yet recruiting
Instituto Hispalense de Pediatria
Seville, 41014
Japan3 sites, 3 recruiting
- Recruiting
Fukuwa Clinic
Chuo-ku, Tokyo, 104-0031
- Recruiting
Maebashi Red Cross Hospital
Maebashi, Gunma, 371-0811
- Recruiting
Saitama City Hospital
Midori, Saitama, 336-8522
About this study
Official title: A PHASE 3 STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF A RESPIRATORY SYNCYTIAL VIRUS VACCINE IN CHILDREN AT HIGH RISK OF RSV DISEASE
The purpose of the study is to evaluate the safety, tolerability, and immunogenicity of RSVpreF in children 5 to <18 years of age at high risk for RSV disease, including those who are immunocompromised.
Read the detailed description
The study will first enroll immunocompetent, RSV-experienced participants before enrolling immunocompromised participants to allow for safety data review. Both Cohorts 1 (chronic conditions) and 2 (immunocompromising conditions) will be stratified into 2 age strata. Cohort 1a will enroll participants 12 to <18 years of age with chronic medical conditions and Cohort 1b will enroll participants 5 to <12 years of age with chronic medical conditions. Cohort 2a will enroll immunocompromised participants 12 to <18 years of age and Cohort 2b will enroll immunocompromised participants 5 to <12 years of age.
- Conditions
- Respiratory Syncytial Virus (RSV)
- Being tested
- RSVpreF, Placebo
- Keywords
- RSV, Vaccine, Pediatric
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
RSVpreFBiological
RSVpreF Vaccine
PlaceboBiological
Placebo
| Study group | Role | What they receive |
|---|---|---|
| Cohort 1: RSVpreF | Experimental | Cohort 1 (a and b): Participants will receive a single dose of RSVpreF at the first study visit. Receives: Biological: RSVpreF |
| Cohort 1: Placebo | Placebo comparator | Cohort 1 (a and b): Participants will receive a single dose of placebo at the first study visit. Receives: Biological: Placebo |
| Cohort 2: RSVpreF/RSVpreF | Experimental | Cohort 2 (a and b): Participants will receive 1 dose of RSVpreF at the first study visit, and 1 dose of RSVpreF at the 12-month visit. Receives: Biological: RSVpreF |
| Cohort 2: RSVpreF/Placebo | Experimental | Cohort 2 (a and b): Participants will receive 1 dose of RSVpreF at the first study visit, and 1 dose of placebo at the 12-month visit. Receives: Biological: RSVpreF; Biological: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Cohort 1: Proportion of participants reporting pre-specified local reactions within 7 days following investigational product administration
Describe pre-specified local reactions in children 5 to <18 years of age with chronic medical conditions
Measured: Within 7 days
Cohort 2: Proportion of participants reporting pre-specified local reactions within 7 days following each investigational product administration
Describe pre-specified local reactions in children 5 to <18 years of age with immunocompromising conditions
Measured: Within 7 days
Cohort 1: Proportion of participants reporting pre-specified systemic events within 7 days following investigational product administration
Describe pre-specified systemic events in children 5 to <18 years of age with chronic medical conditions
Measured: Within 7 days
Cohort 2: Proportion of participants reporting pre-specified systemic events within 7 days following each investigational product administration
Describe pre-specified systemic events in children 5 to <18 years of age with immunocompromising conditions
Measured: Within 7 days
Cohort 1: Proportion of participants reporting adverse events (AEs) through 1 month following investigational product administration
Describe AEs in children 5 to <18 years of age with chronic medical conditions
Measured: From vaccination through 1 month after vaccination
Cohort 2: Proportion of participants reporting adverse events (AEs) through 1 month following last investigational product administration
Describe AEs in children 5 to <18 years of age with immunocompromising conditions
Measured: From vaccination through 1 month after last vaccination
Cohort 1: Proportion of participants reporting serious adverse events (SAEs) throughout the study
Describe SAEs in children 5 to <18 years of age with chronic medical conditions
Measured: From vaccination through 24 months after vaccination
Cohort 2: Proportion of participants reporting serious adverse events (SAEs) throughout the study
Describe SAEs in children 5 to <18 years of age with immunocompromising conditions
Measured: From vaccination through 12 months after last vaccination
Cohort 1: Proportion of participants reporting newly diagnosed chronic medical conditions (NDCMCs) throughout the study
Describe NDCMCs in children 5 to <18 years of age with chronic medical conditions
Measured: From vaccination through 24 months after vaccination
Cohort 2: Proportion of participants reporting newly diagnosed chronic medical conditions (NDCMCs) throughout the study
Describe NDCMCs in children 5 to <18 years of age with immunocompromising conditions
Measured: From vaccination through 12 months after last vaccination
Cohort 1: Geometric mean ratio (GMR), estimated by the ratio of the geometric mean titers (GMTs) for RSV A and RSV B serum neutralizing titers (NTs) 1 month after vaccination in participants in Study C3671017 Cohort 1 compared to those in Study C3671013
Demonstrate that the immune responses elicited by RSVpreF in children 5 to <18 years of age with chronic medical conditions are noninferior to the immune responses in adults ≥60 years of age
Measured: 1 month after vaccination
Cohort 1: Seroresponse rate of RSV A and RSV B serum NTs at 1 month after vaccination
Demonstrate that the immune responses elicited by RSVpreF in children 5 to <18 years of age with chronic medical conditions are noninferior to the immune responses in adults ≥60 years of age.
Seroresponse is defined as a postvaccination NT ≥4 times the lower limit of quantitation (LLOQ) if the prevaccination titer is below the LLOQ; or a ≥4-fold rise from prevaccination if the prevaccination titer is ≥ LLOQ
Measured: 1 month after vaccination
Cohort 2: Neutralizing Titers (NTs) for RSV A and RSV B expressed as Geometric Mean Titers (GMT)
Describe the immune responses elicited by 1 or 2 doses of RSVpreF in children 5 to <18 years of age with immunocompromising conditions
Measured: Before each vaccination, 1 month after each vaccination, 12 months after last vaccination
Cohort 2: NTs for RSV A and RSV B expressed as Geometric Mean Fold Rise (GMFR)
Describe the immune responses elicited by 1 or 2 doses of RSVpreF in children 5 to <18 years of age with immunocompromising conditions
Measured: 1 month after each vaccination, 12 months after last vaccination
Cohort 2: NTs for RSV A and RSV B expressed as seroresponse rate
Describe the immune responses elicited by 1 or 2 doses of RSVpreF in children 5 to <18 years of age with immunocompromising conditions
Measured: 1 month after each vaccination, 12 months after last vaccination
Secondary outcomes (3)
Cohort 1: NTs for RSV A and RSV B expressed as Geometric Mean Titers (GMT)
Describe the immune responses elicited by RSVpreF in children 5 to <18 years of age with chronic medical conditions
Measured: Before vaccination, 1 month after vaccination, 12 months after vaccination, 24 months after vaccination
Cohort 1: NTs for RSV A and RSV B expressed as GMFR
Describe the immune responses elicited by RSVpreF in children 5 to <18 years of age with chronic medical conditions
Measured: 1 month after vaccination, 12 months after vaccination, 24 months after vaccination
Cohort 1: NTs for RSV A and RSV B expressed as seroresponse rate
Describe the immune responses elicited by RSVpreF in children 5 to <18 years of age with chronic medical conditions.
Seroresponse is defined as a postvaccination NT ≥4 times the lower limit of quantitation (LLOQ) if the prevaccination titer is below the LLOQ; or a ≥4-fold rise from prevaccination if the prevaccination titer is ≥ LLOQ
Measured: 1 month after vaccination, 12 months after vaccination, 24 months after vaccination
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Sep 2026
- Study start22 Sep 2026
- Primary completion30 Mar 2031 (estimated)
- Study completion30 Mar 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Respiratory Syncytial Virus (RSV)Studies of the same condition, open and under way.
- More trials run by PfizerThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 920 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07839871
- Sponsor's protocol ID
- C3671017
- Other IDs
- 2026-525797-19-00
- Status last verified
- Oct 2026
- First submitted
- 18 Sep 2026
- Last updated
- 6 Nov 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.
Study at a glance
From the registry record, last updated by the sponsor on 6 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A PHASE 3 STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF A RESPIRATORY SYNCYTIAL VIRUS VACCINE IN CHILDREN AT HIGH RISK OF RSV DISEASE
- ClinicalTrials.gov ID
- NCT07839871
- Acronym / sponsor ID
- C3671017
- Conditions
- Respiratory Syncytial Virus (RSV)
- Keywords
- RSV, Vaccine, Pediatric
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 920 participants (estimated)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 22 Sep 2026 (actual)
- Primary completion
- 30 Mar 2031 (estimated)
- Study completion
- 30 Mar 2031 (estimated)
- First posted
- 24 Sep 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of the study is to evaluate the safety, tolerability, and immunogenicity of RSVpreF in children 5 to <18 years of age at high risk for RSV disease, including those who are immunocompromised.
Detailed description
The study will first enroll immunocompetent, RSV-experienced participants before enrolling immunocompromised participants to allow for safety data review. Both Cohorts 1 (chronic conditions) and 2 (immunocompromising conditions) will be stratified into 2 age strata. Cohort 1a will enroll participants 12 to <18 years of age with chronic medical conditions and Cohort 1b will enroll participants 5 to <12 years of age with chronic medical conditions. Cohort 2a will enroll immunocompromised participants 12 to <18 years of age and Cohort 2b will enroll immunocompromised participants 5 to <12 years of age.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Cohort 1: RSVpreF | Experimental | Biological: RSVpreFCohort 1 (a and b): Participants will receive a single dose of RSVpreF at the first study visit. |
| Cohort 1: Placebo | Placebo comparator | Biological: PlaceboCohort 1 (a and b): Participants will receive a single dose of placebo at the first study visit. |
| Cohort 2: RSVpreF/RSVpreF | Experimental | Biological: RSVpreFCohort 2 (a and b): Participants will receive 1 dose of RSVpreF at the first study visit, and 1 dose of RSVpreF at the 12-month visit. |
| Cohort 2: RSVpreF/Placebo | Experimental | Biological: RSVpreF, Biological: PlaceboCohort 2 (a and b): Participants will receive 1 dose of RSVpreF at the first study visit, and 1 dose of placebo at the 12-month visit. |
Who may qualify
- Ages
- 5 to 17 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child
Key inclusion criteria (21 listed)
- Participants' age requirements for each study cohort at enrollment, respectively Cohort 1a (chronic medical conditions) 12 to <18 years of age Cohort 1b (chronic medical conditions) 5 to <12 years of age Cohort 2a (immunocompromising conditions) 12 to <18 years of age Cohort 2b (immunocompromising conditions) 5 to <12 years of age
- Participants depending on the study cohort requirements, will be considered by the investigator to be at high risk of LRTI-RSV based on the following disease characteristics and definitions:
- Cystic fibrosis
- Medically treated asthma
- Other chronic respiratory diseases and malformations of the lung
Key exclusion criteria (8 listed)
- Applicable to Cohort 1 (a and b) participants only: Immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination
- Applicable to Cohort 1 (a and b) participants only: Individuals with a history of autoimmune disease, past or present, requiring therapeutic intervention including, but not limited to, systemic lupus erythematosus. Note: Stable type 1 diabetes and hypothyroidism are permitted
- History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s)
- Bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection
- Individuals with epilepsy or other seizure disorders that is uncontrolled/unstable, or a history of seizures and/or other neurological complications following vaccination
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| RSVpreFRSVpreF Vaccine | Biological | Cohort 1: RSVpreF, Cohort 2: RSVpreF/Placebo, Cohort 2: RSVpreF/RSVpreF |
| PlaceboPlacebo | Biological | Cohort 1: Placebo, Cohort 2: RSVpreF/Placebo |
Primary outcome
Cohort 1: Proportion of participants reporting pre-specified local reactions within 7 days following investigational product administration
Time frame: Within 7 days
Describe pre-specified local reactions in children 5 to <18 years of age with chronic medical conditions
Cohort 2: Proportion of participants reporting pre-specified local reactions within 7 days following each investigational product administration
Time frame: Within 7 days
Describe pre-specified local reactions in children 5 to <18 years of age with immunocompromising conditions
Cohort 1: Proportion of participants reporting pre-specified systemic events within 7 days following investigational product administration
Time frame: Within 7 days
Describe pre-specified systemic events in children 5 to <18 years of age with chronic medical conditions
Cohort 2: Proportion of participants reporting pre-specified systemic events within 7 days following each investigational product administration
Time frame: Within 7 days
Describe pre-specified systemic events in children 5 to <18 years of age with immunocompromising conditions
Cohort 1: Proportion of participants reporting adverse events (AEs) through 1 month following investigational product administration
Time frame: From vaccination through 1 month after vaccination
Describe AEs in children 5 to <18 years of age with chronic medical conditions
Cohort 2: Proportion of participants reporting adverse events (AEs) through 1 month following last investigational product administration
Time frame: From vaccination through 1 month after last vaccination
Describe AEs in children 5 to <18 years of age with immunocompromising conditions
Cohort 1: Proportion of participants reporting serious adverse events (SAEs) throughout the study
Time frame: From vaccination through 24 months after vaccination
Describe SAEs in children 5 to <18 years of age with chronic medical conditions
Cohort 2: Proportion of participants reporting serious adverse events (SAEs) throughout the study
Time frame: From vaccination through 12 months after last vaccination
Describe SAEs in children 5 to <18 years of age with immunocompromising conditions
Cohort 1: Proportion of participants reporting newly diagnosed chronic medical conditions (NDCMCs) throughout the study
Time frame: From vaccination through 24 months after vaccination
Describe NDCMCs in children 5 to <18 years of age with chronic medical conditions
Cohort 2: Proportion of participants reporting newly diagnosed chronic medical conditions (NDCMCs) throughout the study
Time frame: From vaccination through 12 months after last vaccination
Describe NDCMCs in children 5 to <18 years of age with immunocompromising conditions
Cohort 1: Geometric mean ratio (GMR), estimated by the ratio of the geometric mean titers (GMTs) for RSV A and RSV B serum neutralizing titers (NTs) 1 month after vaccination in participants in Study C3671017 Cohort 1 compared to those in Study C3671013
Time frame: 1 month after vaccination
Demonstrate that the immune responses elicited by RSVpreF in children 5 to <18 years of age with chronic medical conditions are noninferior to the immune responses in adults ≥60 years of age
Cohort 1: Seroresponse rate of RSV A and RSV B serum NTs at 1 month after vaccination
Time frame: 1 month after vaccination
Demonstrate that the immune responses elicited by RSVpreF in children 5 to <18 years of age with chronic medical conditions are noninferior to the immune responses in adults ≥60 years of age. Seroresponse is defined as a postvaccination NT ≥4 times the lower limit of quantitation (LLOQ) if the prevaccination titer is below the LLOQ; or a ≥4-fold rise from prevaccination if the prevaccination titer is ≥ LLOQ
Cohort 2: Neutralizing Titers (NTs) for RSV A and RSV B expressed as Geometric Mean Titers (GMT)
Time frame: Before each vaccination, 1 month after each vaccination, 12 months after last vaccination
Describe the immune responses elicited by 1 or 2 doses of RSVpreF in children 5 to <18 years of age with immunocompromising conditions
Cohort 2: NTs for RSV A and RSV B expressed as Geometric Mean Fold Rise (GMFR)
Time frame: 1 month after each vaccination, 12 months after last vaccination
Describe the immune responses elicited by 1 or 2 doses of RSVpreF in children 5 to <18 years of age with immunocompromising conditions
Cohort 2: NTs for RSV A and RSV B expressed as seroresponse rate
Time frame: 1 month after each vaccination, 12 months after last vaccination
Describe the immune responses elicited by 1 or 2 doses of RSVpreF in children 5 to <18 years of age with immunocompromising conditions
3 secondary outcomes
Cohort 1: NTs for RSV A and RSV B expressed as Geometric Mean Titers (GMT)
Time frame: Before vaccination, 1 month after vaccination, 12 months after vaccination, 24 months after vaccination
Cohort 1: NTs for RSV A and RSV B expressed as GMFR
Time frame: 1 month after vaccination, 12 months after vaccination, 24 months after vaccination
Cohort 1: NTs for RSV A and RSV B expressed as seroresponse rate
Time frame: 1 month after vaccination, 12 months after vaccination, 24 months after vaccination
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Nov 2026.
- To obtain contact information for a study center near you, click here.Link provided by the sponsor.
- Individual participant dataSharing planned: 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.
Related trials for Respiratory Syncytial Virus (RSV)
Active, not recruitingPhase 3
A Study on the Immune Response and Safety of Vaccine Against Respiratory Syncytial Virus Given to Chinese Adults 18 to 59 Years of Age at Increased Risk of Respiratory Syncytial Virus Disease
Respiratory Syncytial Virus Infections
Active, not recruitingPhase 1
A Phase 1 Study to Evaluate JCXH-108, an mRNA-based Vaccine Against RSV
Respiratory Syncytial Virus (RSV), Infectious Disease
RecruitingPhase 2
Immunogenicity of RSVPreF3 Vaccine in Immunocompromised Persons
Respiratory Syncytial Virus (RSV)
RecruitingObservational study
TARSILA Real-World Evidence Study
Respiratory Syncytial Virus (RSV), Maternal Immunization
Not yet recruitingPhase 3
A Study to Evaluate Efficacy, Immunogenicity and Safety of a Recombinant Respiratory Syncytial Virus Vaccine in Older Adults Aged 60 Years and Older
Respiratory Syncytial Virus (RSV), Respiratory Syncytial Virus (RSV) Infection
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Pfizer CT.gov Call Center study director
Pfizer
20 sites in 4 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing RSVpreF in people with Respiratory Syncytial Virus (RSV), run by Pfizer at 20 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 21 inclusion and 8 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 6 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 20 sites in Poland, United States, Spain, Japan. 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?
Cohort 1: Proportion of participants reporting pre-specified local reactions within 7 days following investigational product administration (time frame: Within 7 days). The study lists 15 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 6 Nov 2026.