RESPIRATORY SYNCYTIAL VIRUS (RSV)Phase 1PICASSONCT05900154

A Study to Learn About the Safety and Immune Activity of RSVpreF in Children 2 to <18 Years of Age

A Phase 1 study testing RSVpreF 120 µg and RSVpreF 60 µg in people with RESPIRATORY SYNCYTIAL VIRUS (RSV), run by Pfizer at 17 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

The purpose of this study is to learn about the safety and immune activity of the vaccine (called RSVpreF) in children 2 to <18 years of age. This study will identify the dose level to be used in Phase 2/3 trials in this age cohort. All participants will receive one injection of RSVpreF. Read more about this study

Who is it for?: Ages 2 to 17 yearsHealthy volunteers can take part
Conditions the study is for: RESPIRATORY SYNCYTIAL VIRUS (RSV)
What is being tested?: RSVpreF 120 µg and RSVpreF 60 µg
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 128 participants
Where: 17 sitesUnited States
Study dates: 22 Jun 2023to 29 Feb 2024
Phase: Phase 1
Are there results?: Yes, posted in the registrySummary in the doctors' view

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 2 to 17 years
All sexes
Healthy volunteers accepted
Child

Who may be able to join

Participants 2 to <18 years of age at enrollment
Participants 2 to <18 years of age should either be healthy or be considered by the investigator to be at high risk of RSV disease based on the presence of 1 of the following chronic medical conditions:
Cystic fibrosis
Medically treated asthma
Other chronic respiratory diseases and malformations of the lung
Down syndrome

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Neuromuscular disease
Cerebral palsy
Hemodynamically significant or symptomatic congenital heart disease
All participants 2 to <5 years of age must be seropositive for RSV as confirmed by serology.
Participants' parent(s)/legal guardian(s) and participants, as age appropriate, who are willing and able to comply with all scheduled visits, investigational plan, laboratory tests, and other study procedures, including collection of nasal swabs by participants' parent(s)/legal guardian(s) and by study staff when indicated.
The participant's parent(s)/legal guardian is capable of giving signed informed consent as described 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

Immunocompromised individuals associated with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination.
Individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention, including but not limited to systemic lupus erythematosus. Note: Stable type 1 diabetes and hypothyroidism are permitted.
Other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.
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 a history of epilepsy or other seizure disorders, or a history of seizures and/or other neurological complications following vaccination.

Show all 13Show fewer

Previous vaccination with any licensed or investigational RSV vaccine or planned receipt during study participation. Children who may have been exposed to investigational RSV vaccines through maternal immunization will be permitted.
Receipt of investigational or approved monoclonal antibodies against RSV within 6 months before study intervention administration, or planned receipt throughout the study.
Receipt of blood/plasma products or immunoglobulins within 28 days before study intervention administration, or planned receipt throughout the study.
Receipt of chronic systemic treatment with known immunosuppressant medications (including cytotoxic agents or systemic corticosteroids), or radiotherapy, within 60 days before study intervention administration, or planned receipt throughout the study.
Note: Systemic corticosteroids are defined as those administered for ≥14 days at a dose of ≥20 mg/day of prednisone or equivalent (eg, for cancer or an autoimmune disease). Inhaled/nebulized, intra-articular, intrabursal, or topical (skin, eyes, or ears) corticosteroids are permitted.
Participation in other studies involving study intervention within 28 days prior to study entry and/or for the duration of study participation.
Investigator site staff directly involved in the conduct of the study and their family members, site staff otherwise supervised by the investigator, and sponsor and sponsor delegate employees directly involved in the conduct of the study and their family members.

Trial locations and contacts

17 sites in 1 country.

City, postcode or hospital

17 sites in 1 country

United States17 sites

Innovo Research - Austin Regional Clinic
Austin, Texas, 78726
Velocity Clinical Research, Austin
Austin, Texas, 78759
University of Alabama at Birmingham - School of Medicine
Birmingham, Alabama, 35233
Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, 45229
Duke Vaccine And Trials Unit
Durham, North Carolina, 27703
Velocity Clinical Research, Providence
East Greenwich, Rhode Island, 02818
Velocity Clinical Research, New Orleans
Metairie, Louisiana, 70006
Bio-Medical Research LLC
Miami, Florida, 33144
Velocity Clinical Research, Omaha
Omaha, Nebraska, 68134
Stanford University Medical Center
Palo Alto, California, 94304
Rochester Clinical Research, LLC
Rochester, New York, 14609
Peninsula Research Associates
Rolling Hills Estates, California, 90274
Seattle Children's - Building Cure
Seattle, Washington, 98101
Seattle Children's Hospital
Seattle, Washington, 98105
Velocity Clinical Research, Sioux City
Sioux City, Iowa, 51106
Senders Pediatrics
South Euclid, Ohio, 44121
Velocity Clinical Research, Salt Lake City
West Jordan, Utah, 84088

Other trials in United States

About this study

Official title: A PHASE 1, OPEN-LABEL, AGE-DESCENDING, DOSE-FINDING STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF RESPIRATORY SYNCYTIAL VIRUS PREFUSION F SUBUNIT VACCINE (RSVpreF) IN CHILDREN 2 TO <18 YEARS OF AGE

The purpose of this study is to learn about the safety and immune activity of the vaccine (called RSVpreF) in children 2 to <18 years of age.

This study will identify the dose level to be used in Phase 2/3 trials in this age cohort. All participants will receive one injection of RSVpreF. This study has four study visits, two in-clinic and two telehealth visits. Blood samples will be collected for testing. This study is about 6 months long for each participant and will be conducted in the United States.

Conditions: RESPIRATORY SYNCYTIAL VIRUS (RSV)
Being tested: RSVpreF 120 µg, RSVpreF 60 µg
Keywords: RESPIRATORY SYNCYTIAL VIRUS, RSV, RSV vaccine, Respiratory illness, Respiratory infection, Pediatric
Medical subject headings: Respiratory Tract Infections

What participants receive

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

RSVpreF 120 µgBiological
RSVpreF standard dose level
RSVpreF 60 µgBiological
RSVpreF low dose level

Study groups in NCT05900154
Study group	Role	What they receive
standard dose in 5 to <18 years olds, healthy	Experimental	standard dose (120 µg) Receives: Biological: RSVpreF 120 µg
standard dose in 5 to < 18 years olds, with chronic high risk conditions	Experimental	standard dose (120 µg) Receives: Biological: RSVpreF 120 µg
standard dose in 2 to < 5 years olds	Experimental	standard dose (120 µg) Receives: Biological: RSVpreF 120 µg
low dose in 5 to <18 years olds, healthy	Experimental	low dose (60 µg) Receives: Biological: RSVpreF 60 µg
low dose in 5 to <18 years olds, with chronic high risk conditions	Experimental	low dose (60 µg) Receives: Biological: RSVpreF 60 µg
low dose in 2 to < 5 years olds	Experimental	low dose (60 µg) Receives: Biological: RSVpreF 60 µg

What is being measured

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

Percentage of Participants With Local Reactions Within 7 Days After Vaccination
Local reactions were collected in the electronic diary (e-diary) from Day 1 through Day 7 after vaccination. Local reactions included pain at injection site, redness, and swelling. For participants greater than or equal to (>=) 2 years to <12 years of age, redness and swelling were graded as mild: 0.5 to 2.0 centimeter (cm), moderate: >2.0 to 7.0 cm, and severe: > 7 cm; for participants >=12 years of age, mild: > 2.0 to 5.0 cm, moderate: >5.0 to 10.0 cm, and severe: >10 cm. Pain at injection site was graded as mild (did not interfere with activity), moderate (interfered with activity), and severe (prevented daily activity).
Measured: Day 1 through Day 7 after Vaccination
Percentage of Participants With Systemic Events Within 7 Days After Vaccination
Systemic events included fever, fatigue, headache, vomiting, diarrhea, muscle pain and joint pain and were recorded by participants using e-diary. Fever: oral temperature >= 38.0 degree Celsius (deg C) and categorized as >=38.0 to 38.4 deg C (mild), >38.4 to 38.9 deg C (moderate), and >38.9 to 40.0 deg C (severe). Fatigue, headache, muscle pain and joint pain were graded as mild (did not interfere with activity), moderate (some interference with activity), and severe (prevented daily routine activity). Vomiting was graded mild: 1-2 times in 24 hours (h), moderate: >2 times in 24h, and severe: required intravenous hydration. Diarrhea was graded mild: 2-3 loose stools in 24h, moderate: 4-5 loose stools in 24h and severe: 6 or more loose stools in 24h.
Measured: Day 1 through Day 7 after Vaccination
Percentage of Participants With Adverse Events (AEs) Within 1 Month After Vaccination
AE was defined as any untoward medical occurrence in clinical study participant, temporally associated with use of study intervention, whether or not considered related to study intervention. AEs included serious and all non-serious AE. SAEs were defined as AE that, at any dose: resulted in death; was life-threatening; required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent disability/incapacity; was congenital anomaly or birth defect; was suspected transmission via Pfizer product of infectious agent, pathogenic or nonpathogenic or was considered to be an important medical event. Only AEs collected by non-systematic assessment (i.e., excluding local reactions and systemic events) were included.
Measured: Within 1 month post Vaccination
Percentage of Participants With Serious Adverse Events (SAEs) Throughout the Study
An AE was defined as any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. SAEs were defined as an AE that, at any dose: resulted in death; was life-threatening; required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent disability or incapacity; was a congenital anomaly or birth defect; was a suspected transmission via a Pfizer product of an infectious agent, pathogenic or nonpathogenic or that was considered to be an important medical event.
Measured: Within 6 months post Vaccination
Percentage of Participants Reporting Newly Diagnosed Chronic Medical Condition (NDCMCs) Throughout the Study
An NDCMC was defined as a disease or medical condition, which was not previously identified, that was expected to be persistent or otherwise long-lasting in its effects.
Measured: Within 6 months post Vaccination

Secondary outcomes (3)

Geometric Mean Titer of the Neutralizing Titers for RSV A and RSV B Before Vaccination and 1 Month After Vaccination
Geometric mean titer (GMT) of neutralizing titers (NTs) of respiratory syncytial virus subgroup A and respiratory syncytial virus subgroup B (RSV A and RSV B) before vaccination and 1 month after vaccination were reported in this outcome measure. Assay results below the lower limit of quantification (LLOQ) were set to 0.5*LLOQ. GMTs and corresponding 2-sided CIs were calculated by exponentiating mean logarithm of titers and corresponding CIs (based on Student's t distribution).
Measured: Before vaccination and 1 month after vaccination
Geometric Mean Fold Rise (GMFR) of the NTs for RSV A and RSV B From Before Vaccination to 1 Month After Vaccination
GMFR of neutralizing titers of RSV A and RSV B from before vaccination to 1 month after vaccination were reported in this outcome measure. GMFR and the corresponding 2-sided CIs were calculated by exponentiating the mean logarithm of the fold rises and the corresponding CIs (based on the Student's t distribution).
Measured: From before vaccination to 1 month after vaccination
Median Frequencies of RSV F Antigen-Specific Cluster of Differentiation 4 (CD4+) Thymus-Derived Lymphocytes (T) Cells Expressing Interferon (IFN) Gamma and Interleukin-4 (IL-4) Before Vaccination and 1 Month After Vaccination
Median frequencies of RSV F antigen-specific CD4+ T cells expressing IFN gamma and IL-4 before vaccination and 1 month after vaccination were reported in this outcome measure. RSV F enzyme-linked immune absorbent spot assay (ELISpot) limit of detection (LOD) values were IFN gamma = 20 spot forming cell (SFC) per million peripheral blood mononuclear cell (PBMCs) and IL-4 = 4 SFC/million PBMCs. Assay results below LOD=0.5*LOD for analysis. Frequencies were defined as the count of the RSV F antigen-specific CD4+ T cells and median frequencies were defined as the median of the counts.
Measured: Before vaccination and 1 Month after vaccination

Timeline

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

22 Jun 202329 Feb 2024

First posted12 Jun 2023
Study start22 Jun 2023
Primary completion29 Feb 2024
Study completion29 Feb 2024

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
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 1
Primary purpose: Prevention
Allocation: Randomised
Intervention model: Sequential
Model description: This is an open-label dose-finding study. A single dose of RSVpreF 120 µg will be given to 40 participants in the 5 to \<18 age group first. Upon safety review and approval, a dose of 60 µg will be given to 20 participants in the 2 to \<5 age group. If, 60 µg is safe, another 20 participants in the 2 to \<5- age group will receive the 120-µg dose. Approximately 60 to 120 participants are expected to be enrolled.
Masking: None (open label)
Enrolment: 128 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT05900154
Sponsor's protocol ID: C3671016
Other IDs: 2024-000422-17
Acronym: PICASSO
Status last verified: Feb 2025
First submitted: 2 Jun 2023
Last updated: 6 Mar 2025
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: No: 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.

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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RecruitingPhase 2
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All RESPIRATORY SYNCYTIAL VIRUS (RSV) trials

Study at a glance

From the registry record, last updated by the sponsor on 6 Mar 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A PHASE 1, OPEN-LABEL, AGE-DESCENDING, DOSE-FINDING STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF RESPIRATORY SYNCYTIAL VIRUS PREFUSION F SUBUNIT VACCINE (RSVpreF) IN CHILDREN 2 TO <18 YEARS OF AGE
ClinicalTrials.gov ID: NCT05900154
Acronym / sponsor ID: PICASSO / C3671016
Conditions: RESPIRATORY SYNCYTIAL VIRUS (RSV)
Keywords: RESPIRATORY SYNCYTIAL VIRUS, RSV, RSV vaccine, Respiratory illness, Respiratory infection, Pediatric
Phase: Phase 1
Study type: Interventional
Recruitment status: Completed
Enrolment: 128 participants (actual)
Lead sponsor: PfizerIndustry (pharma, biotech, devices)
Study start: 22 Jun 2023 (actual)
Primary completion: 29 Feb 2024 (actual)
Study completion: 29 Feb 2024 (actual)
First posted: 12 Jun 2023 (actual)
Results: Posted 6 Mar 2025

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 this study is to learn about the safety and immune activity of the vaccine (called RSVpreF) in children 2 to <18 years of age.

Study design

Primary purpose: Prevention
Allocation: Randomised
Intervention model: Sequential
Masking: None (open label)
Number of arms: 6
Model description: This is an open-label dose-finding study. A single dose of RSVpreF 120 µg will be given to 40 participants in the 5 to <18 age group first. Upon safety review and approval, a dose of 60 µg will be given to 20 participants in the 2 to <5 age group. If, 60 µg is safe, another 20 participants in the 2 to <5- age group will receive the 120-µg dose. Approximately 60 to 120 participants are expected to be enrolled.

Arm	Type	Receives
standard dose in 5 to <18 years olds, healthy	Experimental	Biological: RSVpreF 120 µgstandard dose (120 µg)
standard dose in 5 to < 18 years olds, with chronic high risk conditions	Experimental	Biological: RSVpreF 120 µgstandard dose (120 µg)
standard dose in 2 to < 5 years olds	Experimental	Biological: RSVpreF 120 µgstandard dose (120 µg)
low dose in 5 to <18 years olds, healthy	Experimental	Biological: RSVpreF 60 µglow dose (60 µg)
low dose in 5 to <18 years olds, with chronic high risk conditions	Experimental	Biological: RSVpreF 60 µglow dose (60 µg)
low dose in 2 to < 5 years olds	Experimental	Biological: RSVpreF 60 µglow dose (60 µg)

Who may qualify

Ages: 2 to 17 years
Sex: All
Healthy volunteers: Accepted
Age groups: Child

Key inclusion criteria (12 listed)

Participants 2 to <18 years of age at enrollment
Participants 2 to <18 years of age should either be healthy or be considered by the investigator to be at high risk of RSV disease based on the presence of 1 of the following chronic medical conditions:
All participants 2 to <5 years of age must be seropositive for RSV as confirmed by serology.
Participants' parent(s)/legal guardian(s) and participants, as age appropriate, who are willing and able to comply with all scheduled visits, investigational plan, laboratory tests, and other study procedures, including collection of nasal swabs by participants' parent(s)/legal guardian(s) and by study staff when indicated.
The participant's parent(s)/legal guardian is capable of giving signed informed consent as described 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).

Key exclusion criteria (13 listed)

Immunocompromised individuals associated with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination.
Individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention, including but not limited to systemic lupus erythematosus. Note: Stable type 1 diabetes and hypothyroidism are permitted.
Other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.
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.

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
RSVpreF 120 µgRSVpreF standard dose level	Biological	standard dose in 2 to < 5 years olds, standard dose in 5 to < 18 years olds, with chronic high risk conditions, standard dose in 5 to <18 years olds, healthy
RSVpreF 60 µgRSVpreF low dose level	Biological	low dose in 2 to < 5 years olds, low dose in 5 to <18 years olds, healthy, low dose in 5 to <18 years olds, with chronic high risk conditions

Primary outcome

Percentage of Participants With Local Reactions Within 7 Days After Vaccination
Time frame: Day 1 through Day 7 after Vaccination
Local reactions were collected in the electronic diary (e-diary) from Day 1 through Day 7 after vaccination. Local reactions included pain at injection site, redness, and swelling. For participants greater than or equal to (>=) 2 years to <12 years of age, redness and swelling were graded as mild: 0.5 to 2.0 centimeter (cm), moderate: >2.0 to 7.0 cm, and severe: > 7 cm; for participants >=12 years of age, mild: > 2.0 to 5.0 cm, moderate: >5.0 to 10.0 cm, and severe: >10 cm. Pain at injection site was graded as mild (did not interfere with activity), moderate (interfered with activity), and severe (prevented daily activity).
Percentage of Participants With Systemic Events Within 7 Days After Vaccination
Time frame: Day 1 through Day 7 after Vaccination
Systemic events included fever, fatigue, headache, vomiting, diarrhea, muscle pain and joint pain and were recorded by participants using e-diary. Fever: oral temperature >= 38.0 degree Celsius (deg C) and categorized as >=38.0 to 38.4 deg C (mild), >38.4 to 38.9 deg C (moderate), and >38.9 to 40.0 deg C (severe). Fatigue, headache, muscle pain and joint pain were graded as mild (did not interfere with activity), moderate (some interference with activity), and severe (prevented daily routine activity). Vomiting was graded mild: 1-2 times in 24 hours (h), moderate: >2 times in 24h, and severe: required intravenous hydration. Diarrhea was graded mild: 2-3 loose stools in 24h, moderate: 4-5 loose stools in 24h and severe: 6 or more loose stools in 24h.
Percentage of Participants With Adverse Events (AEs) Within 1 Month After Vaccination
Time frame: Within 1 month post Vaccination
AE was defined as any untoward medical occurrence in clinical study participant, temporally associated with use of study intervention, whether or not considered related to study intervention. AEs included serious and all non-serious AE. SAEs were defined as AE that, at any dose: resulted in death; was life-threatening; required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent disability/incapacity; was congenital anomaly or birth defect; was suspected transmission via Pfizer product of infectious agent, pathogenic or nonpathogenic or was considered to be an important medical event. Only AEs collected by non-systematic assessment (i.e., excluding local reactions and systemic events) were included.
Percentage of Participants With Serious Adverse Events (SAEs) Throughout the Study
Time frame: Within 6 months post Vaccination
An AE was defined as any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. SAEs were defined as an AE that, at any dose: resulted in death; was life-threatening; required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent disability or incapacity; was a congenital anomaly or birth defect; was a suspected transmission via a Pfizer product of an infectious agent, pathogenic or nonpathogenic or that was considered to be an important medical event.
Percentage of Participants Reporting Newly Diagnosed Chronic Medical Condition (NDCMCs) Throughout the Study
Time frame: Within 6 months post Vaccination
An NDCMC was defined as a disease or medical condition, which was not previously identified, that was expected to be persistent or otherwise long-lasting in its effects.

3 secondary outcomes

Geometric Mean Titer of the Neutralizing Titers for RSV A and RSV B Before Vaccination and 1 Month After Vaccination
Time frame: Before vaccination and 1 month after vaccination
Geometric Mean Fold Rise (GMFR) of the NTs for RSV A and RSV B From Before Vaccination to 1 Month After Vaccination
Time frame: From before vaccination to 1 month after vaccination
Median Frequencies of RSV F Antigen-Specific Cluster of Differentiation 4 (CD4+) Thymus-Derived Lymphocytes (T) Cells Expressing Interferon (IFN) Gamma and Interleukin-4 (IL-4) Before Vaccination and 1 Month After Vaccination
Time frame: Before vaccination and 1 Month after vaccination

Results and safety

Results posted to the registry on 6 Mar 2025, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
RSVpreF 120 Micrograms (mcg): 5 to <18 Years [Healthy Participants]	25	25
RSVpreF 120 mcg: 5 to <18 Years [High Risk Participants]	23	23
RSVpreF 120 mcg: 2 to < 5 Years	24	24
RSVpreF 60 mcg: 5 to <18 Years [Healthy Participants]	17	17
RSVpreF 60 mcg: 5 to <18 Years [High Risk Participants]	18	18
RSVpreF 60 mcg: 2 to < 5 Years	20	20

Primary outcome: Percentage of Participants With Local Reactions Within 7 Days After Vaccination

Time frame: Day 1 through Day 7 after Vaccination. Number (95% Confidence Interval). Unit: Percentage of participants

Measure	RSVpreF 120 mcg: 5 to <18 Years [Healthy Participants] n = 25	RSVpreF 120 mcg: 5 to <18 Years [High Risk Participants] n = 23	RSVpreF 120 mcg: 2 to <5 Years n = 24	RSVpreF 60 mcg: 5 to <18 Years [Healthy Participants] n = 17	RSVpreF 60 mcg: 5 to <18 Years [High Risk Participants] n = 18	RSVpreF 60 mcg: 2 to <5 Years n = 20
Pain at injection site: Mild	36.0 (18.0 to 57.5)	39.1 (19.7 to 61.5)	8.3 (1.0 to 27.0)	35.3 (14.2 to 61.7)	33.3 (13.3 to 59.0)	15.0 (3.2 to 37.9)
Pain at injection site: Moderate	8.0 (1.0 to 26.0)	8.7 (1.1 to 28.0)	0 (0.0 to 14.2)	5.9 (0.1 to 28.7)	22.2 (6.4 to 47.6)	0 (0.0 to 16.8)
Pain at injection site: Severe	4.0 (0.1 to 20.4)	0 (0.0 to 14.8)	0 (0.0 to 14.2)	0 (0.0 to 19.5)	0 (0.0 to 18.5)	0 (0.0 to 16.8)
Redness: Mild	12.0 (2.5 to 31.2)	4.3 (0.1 to 21.9)	12.5 (2.7 to 32.4)	0 (0.0 to 19.5)	11.1 (1.4 to 34.7)	5.0 (0.1 to 24.9)
Redness: Moderate	12.0 (2.5 to 31.2)	4.3 (0.1 to 21.9)	0 (0.0 to 14.2)	5.9 (0.1 to 28.7)	0 (0.0 to 18.5)	0 (0.0 to 16.8)
Redness: Severe	0 (0.0 to 13.7)	0 (0.0 to 14.8)	0 (0.0 to 14.2)	0 (0.0 to 19.5)	0 (0.0 to 18.5)	0 (0.0 to 16.8)
Swelling: Mild	4.0 (0.1 to 20.4)	0 (0.0 to 14.8)	4.2 (0.1 to 21.1)	0 (0.0 to 19.5)	11.1 (1.4 to 34.7)	0 (0.0 to 16.8)
Swelling: Moderate	8.0 (1.0 to 26.0)	8.7 (1.1 to 28.0)	0 (0.0 to 14.2)	5.9 (0.1 to 28.7)	11.1 (1.4 to 34.7)	5.0 (0.1 to 24.9)

Population analysed: Safety population included all enrolled participants who received study intervention.

Primary outcome: Percentage of Participants With Systemic Events Within 7 Days After Vaccination

Time frame: Day 1 through Day 7 after Vaccination. Number (95% Confidence Interval). Unit: Percentage of participants

Measure	RSVpreF 120 mcg: 5 to <18 Years [Healthy Participants] n = 25	RSVpreF 120 mcg: 5 to <18 Years [High Risk Participants] n = 23	RSVpreF 120 mcg: 2 to <5 Years n = 24	RSVpreF 60 mcg: 5 to <18 Years [Healthy Participants] n = 17	RSVpreF 60 mcg: 5 to <18 Years [High Risk Participants] n = 18	RSVpreF 60 mcg: 2 to < 5 Years n = 20
Fever: Mild	0 (0.0 to 13.7)	4.3 (0.1 to 21.9)	4.2 (0.1 to 21.1)	0 (0.0 to 19.5)	0 (0.0 to 18.5)	5.0 (0.1 to 24.9)
Fever: Moderate	0 (0.0 to 13.7)	0 (0.0 to 14.8)	0 (0.0 to 14.2)	0 (0.0 to 19.5)	5.6 (0.1 to 27.3)	0 (0.0 to 16.8)
Fever: Severe	0 (0.0 to 13.7)	0 (0.0 to 14.8)	0 (0.0 to 14.2)	5.9 (0.1 to 28.7)	5.6 (0.1 to 27.3)	0 (0.0 to 16.8)
Fatigue: Mild	20.0 (6.8 to 40.7)	21.7 (7.5 to 43.7)	20.8 (7.1 to 42.2)	41.2 (18.4 to 67.1)	16.7 (3.6 to 41.4)	30.0 (11.9 to 54.3)
Fatigue: Moderate	12.0 (2.5 to 31.2)	21.7 (7.5 to 43.7)	8.3 (1.0 to 27.0)	5.9 (0.1 to 28.7)	33.3 (13.3 to 59.0)	5.0 (0.1 to 24.9)
Fatigue: Severe	0 (0.0 to 13.7)	0 (0.0 to 14.8)	0 (0.0 to 14.2)	0 (0.0 to 19.5)	0 (0.0 to 18.5)	0 (0.0 to 16.8)
Headache: Mild	16.0 (4.5 to 36.1)	26.1 (10.2 to 48.4)	0 (0.0 to 14.2)	29.4 (10.3 to 56.0)	16.7 (3.6 to 41.4)	0 (0.0 to 16.8)
Headache: Moderate	12.0 (2.5 to 31.2)	8.7 (1.1 to 28.0)	4.2 (0.1 to 21.1)	11.8 (1.5 to 36.4)	16.7 (3.6 to 41.4)	0 (0.0 to 16.8)

Population analysed: Safety population included all enrolled participants who received study intervention.

Primary outcome: Percentage of Participants With Adverse Events (AEs) Within 1 Month After Vaccination

Time frame: Within 1 month post Vaccination. Number (95% Confidence Interval). Unit: Percentage of participants

Measure	RSVpreF 120 mcg: 5 to <18 Years [Healthy Participants] n = 25	RSVpreF 120 mcg: 5 to <18 Years [High Risk Participants] n = 23	RSVpreF 120 mcg: 2 to <5 Years n = 24	RSVpreF 60 mcg: 5 to <18 Years [Healthy Participants] n = 17	RSVpreF 60 mcg: 5 to <18 Years [High Risk Participants] n = 18	RSVpreF 60 mcg: 2 to <5 Years n = 20
Value	0 (0.0 to 13.7)	17.4 (5.0 to 38.8)	12.5 (2.7 to 32.4)	0 (0.0 to 19.5)	27.8 (9.7 to 53.5)	15.0 (3.2 to 37.9)

Population analysed: Safety population included all enrolled participants who received study intervention.

Primary outcome: Percentage of Participants With Serious Adverse Events (SAEs) Throughout the Study

Time frame: Within 6 months post Vaccination. Number (95% Confidence Interval). Unit: Percentage of participants

Measure	RSVpreF 120 mcg: 5 to <18 Years [Healthy Participants] n = 25	RSVpreF 120 mcg: 5 to <18 Years [High Risk Participants] n = 23	RSVpreF 120 mcg: 2 to <5 Years n = 24	RSVpreF 60 mcg: 5 to <18 Years [Healthy Participants] n = 17	RSVpreF 60 mcg: 5 to <18 Years [High Risk Participants] n = 18	RSVpreF 60 mcg: 2 to <5 Years n = 20
Value	0 (0.0 to 13.7)	4.3 (0.1 to 21.9)	0 (0.0 to 14.2)	0 (0.0 to 19.5)	5.6 (0.1 to 27.3)	0 (0.0 to 16.8)

Population analysed: Safety population included all enrolled participants who received study intervention.

3 secondary outcomes are reported in the full results.

Adverse events

Time frame: Local reactions and systemic events: Within 7 days after vaccination. SAEs: Within 6 months post Vaccination and other AEs: Within 1 month post Vaccination. Other adverse events reported at 5% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Healthy RSVpreF 120 Micrograms (mcg)	0 of 25 (0%)	17 of 25 (68%)	0 of 25
High Risk RSVpreF 120 mcg	1 of 23 (4.3%)	15 of 23 (65.2%)	0 of 23
2 to < 5 Years RSVpreF 120 mcg	0 of 24 (0%)	9 of 24 (37.5%)	0 of 24
Healthy RSVpreF 60 mcg	0 of 17 (0%)	12 of 17 (70.6%)	0 of 17
High Risk RSVpreF 60 mcg	1 of 18 (5.6%)	14 of 18 (77.8%)	0 of 18
2 to < 5 Years RSVpreF 60 mcg	0 of 20 (0%)	13 of 20 (65%)	0 of 20

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 6 Mar 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
To obtain contact information for a study center near you, click here.Link provided by the sponsor.
Individual participant dataSharing planned: No. 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.

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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. This study is not recruiting at the moment.

Pfizer CT.gov Call Center study director

Pfizer

17 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing RSVpreF 120 µg and RSVpreF 60 µg in people with RESPIRATORY SYNCYTIAL VIRUS (RSV), run by Pfizer at 17 sites in United States.

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 12 inclusion and 13 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: finished, as of the sponsor's last update on 6 Mar 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 17 sites in United States. 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. 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 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

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

Are results available for this study?

Yes. Results are posted in the registry (first posted 6 Mar 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

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

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Percentage of Participants With Local Reactions Within 7 Days After Vaccination (time frame: Day 1 through Day 7 after Vaccination). The study lists 5 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 NCT05900154.

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 Mar 2025.