Respiratory Syncytial Virus InfectionsPhase 1NCT06102174

A Study to Learn About the Amount of the Study Medicine (Sisunatovir) in Blood and Its Safety in Infants and Children With Pneumonia Caused by RSV

A Phase 1 study testing Active in people with Respiratory Syncytial Virus Infections, run by Pfizer at 9 sites in 3 countries.

Terminated

Stopped early. The study ended before it was planned to and will not resume.

Official record

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Trial summary

The purpose of the study is to learn about the safety and amount of sisunatovir in the blood of infants and children up to age 60 months. These children have Lower Respiratory Tract Infection (LRTI) caused by Respiratory Syncytial Virus (RSV). LRTI is the infection to the lower airways such as lungs. Read more about this study

Who is it for?: Ages 1 day to 60 months
Conditions the study is for: Respiratory Syncytial Virus Infections
What is being tested?: Active
Type of treatment: Pill or oral medicine
Could I receive a placebo?: Yes, some participants may receive a placebo
How many people: 10 participants
Where: 9 sitesin 3 countries
Study dates: 15 Feb 2024to 3 Sep 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 1 day to 60 months
All sexes
No healthy volunteers
Child

Who may be able to join

1 day to ≤60 months of age and weight ≥2.5 kg to ≤23 kg
Positive RSV diagnostic test, antigen or molecular test
Evidence of Lower Respiratory Tract Infection (LRTI)

Who cannot join

Premature infants (gestational age less than 35 weeks) AND <1 year of post-natal age
Neonates with intrauterine growth restriction
Expected to receive an antiviral for another viral infection within 10 days of screening
Suspected or confirmed clinically significant moderate or severe bacterial infection that may interfere with the evaluation of response to the study intervention
Known to have significant comorbidities that would limit the ability to administer the study intervention or evaluate the safety or clinical response to the study intervention

Trial locations and contacts

9 sites in 3 countries.

Country

City, postcode or hospital

9 sites in 3 countries

Japan4 sites

Nintenkai Kagoshima Children's Hospital
Hioki, Kagoshima-ken, 899-2503
Yamanashi Prefectural Central Hospital
Kofu, Yamanashi, 400-8506
Kojunkai Daido Hospital
Nagoya, Aichi-ken, 457-8511
Osaka City General Hospital
Osaka, 534-0021

Other trials in Japan

United States3 sites

Kaiser Permanente Los Angeles Medical center
Los Angeles, California, 90027
Kaiser Permanente
Los Angeles, California, 90027
Washington University School of Medicine
St Louis, Missouri, 63110

Other trials in United States

South Africa2 sites

University of Witwatersrand (WITS) - Vaccines and Infectious Diseases Analytics (VIDA)
Johannesburg, Gauteng, 2013
Monti Clinical Research Centre
Mdantsane, Eastern Cape, 5219

Other trials in South Africa

About this study

Official title: AN INTERVENTIONAL, PHASE 1b, RANDOMIZED, DOUBLE-BLIND, SPONSOR-OPEN, PLACEBO-CONTROLLED, MULTI-CENTER, DOSE-FINDING STUDY TO EVALUATE SAFETY, TOLERABILITY AND PHARMACOKINETICS OF SISUNATOVIR IN PEDIATRIC PARTICIPANTS UP TO AGE 60 MONTHS WITH RESPIRATORY SYNCYTIAL VIRUS (RSV) LOWER RESPIRATORY TRACT INFECTION (LRTI)

This study will help inform the amount of sisunatovir to be used in future studies of sisunatovir in children.

This study is seeking for participants who:

Are 1 day to less than or equal to 60 months of age
weigh more than or equal to 2.5 kilograms to less than or equal to 23 kilograms.
Have been tested to have RSV by medical tests.
show signs of LRTI.

All participants in the study will receive many amounts of sisunatovir or placebo. Placebo is a pill that does not have any medicine in it.

Up to 7 visits are required for the study. Some of these visits include checking participants health over the phone and/or a visit at home.

The study will compare the experiences of infants and children receiving sisunatovir to identify the amount of sisunatovir to be used in future studies in infants and children.

Conditions: Respiratory Syncytial Virus Infections
Being tested: Placebo, Active
Keywords: Lower Respiratory Tract Infection
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.

PlaceboDrug
Placebo
ActiveDrug
Also called PF-07923568, RV521
Sisunatovir

Study groups in NCT06102174
Study group	Role	What they receive
Placebo	Placebo comparator	Oral or Nasogastric tube (NG) Receives: Drug: Placebo
Sisunatovir	Active comparator	Oral or NG tube Receives: Drug: Active

What is being measured

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

Number of Participants With Treatment Emergent Adverse Events (TEAEs)
An adverse event (AE) was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs. All AEs were included for evaluation.
Measured: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
Number of Participants Who Discontinued From Study Due to TEAEs
An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs.
Measured: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
Number of Participants Who Discontinued From Study Due to Serious TEAEs
An AE was any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs. A serious AE (SAE) was any untoward medical occurrence at any dose that: resulted in death; was life-threatening experience (immediate risk of death); required inpatient hospitalization or prolongation if existing hospitalization; resulted in persistent or significant disability/ incapacity; resulted in congenital anomaly/birth defect; other important event or situation as pre-specified in protocol.
Measured: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
Number of Participants With Clinically Significant Laboratory Abnormalities
Following parameters were analyzed for laboratory examination: hematology (hemoglobin, hematocrit, red blood cell count, platelet count, white blood cell count, mean cell volume, mean cell hemoglobin \& concentration); chemistry: urea and creatinine, estimated glomerular filtration rate (eGFR), gamma-glutamyl transferase (GGT), calcium, sodium, potassium, chloride, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin, alkaline phosphatase, albumin, total protein, cystatin C; urinalysis: pH, glucose, protein, blood, ketones, nitrites, leukocyte esterase, albumin, creatinine (urine), urine albumin to creatinine ratio. Clinically significant laboratory abnormalities findings were based on investigator discretion.
Measured: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
Number of Participants With Clinically Significant Vital Signs
Vital signs included systolic and diastolic blood pressure, pulse rate/heart rate, temperature, respiratory rate, and oxygen saturation. Clinically significance vital signs findings were based on investigator discretion.
Measured: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)

Secondary outcomes (1)

Plasma Concentrations Versus Time Summary of Sisunatovir
Measured: Day 3: Pre-dose, T1 and T2 hours post-dose; Day 5: Pre-dose; where T1 is the first analysis time point post-dose while T2 is the second analysis time point post-dose

Timeline

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

15 Feb 20243 Sep 2024

First posted26 Oct 2023
Study start15 Feb 2024
Primary completion3 Sep 2024
Study completion3 Sep 2024

Why it stopped: Study discontinued due to business reasons. There were no safety concerns in the decision to stop study and no changes to sponsor's assessment of the risk-benefit profile for participants who received sisunatovir in the study

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.
Publications (1)Papers the sponsor has linked to this study.
Other trials for Respiratory Syncytial Virus InfectionsStudies 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: Other
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind
Who is masked: Participant, Care provider, Investigator
Enrolment: 10 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06102174
Sponsor's protocol ID: C5241009
Other IDs: 2023-504425-39-00, 2023
Status last verified: Dec 2025
First submitted: 6 Oct 2023
Last updated: 30 Dec 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.

Publications

Toussi SS, Calvo C, Haumann B, Thomas E, Franke RM, Kudela M, Zhang S, Banerjee A, Rees S, Shoji S, Welch H, Jordan I, Srisingh K, Daud M, Nemeth A, Rojo P, Toh TH, Ogunade I, Oku S, Amo K, Towner W, Newland J, Alami NN. Safety and Pharmacokinetics of the RSV Fusion Inhibitor Sisunatovir Across Two Early-phase Studies in Infants and Children With RSV Lower Respiratory Tract Infection. Pediatr Infect Dis J. 2026 Aug 1;45(8):724-732. doi: 10.1097/INF.0000000000005169. Epub 2026 Feb 12.
PubMed 41673909

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

Active, not recruitingPhase 1/2
A Study to Characterize the Safety and Immunogenicity of AZD6489 in Participants 60 Years of Age and Older (ARIES)
RSV Respiratory Syncytial Virus
Recruiting
RSV Burden in Outpatient and Hospital Settings
RSV Infection, Children, Only
Active, not recruitingObservational study
SPECIAL INVESTIGATION FOR ABRYSVO IN INDIVIDUALS AGED 60 YEARS OR OLDER
Respiratory Syncytial Virus Infection
Not yet recruiting
Short-Term Enteral Nutrition for Infants With Bronchiolitis in Pediatric Emergency Departments
Bronchiolitis, Clinical Phenotype
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RSV Vaccine in Transplant Recipients
Vaccine Response Impaired, Respiratory Syncytial Virus Infections

All Respiratory Syncytial Virus Infections trials

Study at a glance

From the registry record, last updated by the sponsor on 30 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: AN INTERVENTIONAL, PHASE 1b, RANDOMIZED, DOUBLE-BLIND, SPONSOR-OPEN, PLACEBO-CONTROLLED, MULTI-CENTER, DOSE-FINDING STUDY TO EVALUATE SAFETY, TOLERABILITY AND PHARMACOKINETICS OF SISUNATOVIR IN PEDIATRIC PARTICIPANTS UP TO AGE 60 MONTHS WITH RESPIRATORY SYNCYTIAL VIRUS (RSV) LOWER RESPIRATORY TRACT INFECTION (LRTI)
ClinicalTrials.gov ID: NCT06102174
Acronym / sponsor ID: C5241009
Conditions: Respiratory Syncytial Virus Infections
Keywords: Lower Respiratory Tract Infection
Phase: Phase 1
Study type: Interventional
Recruitment status: TerminatedReason stopped: Study discontinued due to business reasons. There were no safety concerns in the decision to stop study and no changes to sponsor's assessment of the risk-benefit profile for participants who received sisunatovir in the study
Enrolment: 10 participants (actual)
Lead sponsor: PfizerIndustry (pharma, biotech, devices)
Study start: 15 Feb 2024 (actual)
Primary completion: 3 Sep 2024 (actual)
Study completion: 3 Sep 2024 (actual)
First posted: 26 Oct 2023 (actual)
Results: Posted 30 Dec 2025

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

This study will help inform the amount of sisunatovir to be used in future studies of sisunatovir in children.

This study is seeking for participants who:

Are 1 day to less than or equal to 60 months of age
weigh more than or equal to 2.5 kilograms to less than or equal to 23 kilograms.
Have been tested to have RSV by medical tests.
show signs of LRTI.

All participants in the study will receive many amounts of sisunatovir or placebo. Placebo is a pill that does not have any medicine in it.

Up to 7 visits are required for the study. Some of these visits include checking participants health over the phone and/or a visit at home.

The study will compare the experiences of infants and children receiving sisunatovir to identify the amount of sisunatovir to be used in future studies in infants and children.

Study design

Primary purpose: Other
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind (participant, care provider, investigator)
Number of arms: 2

Arm	Type	Receives
Placebo	Placebo comparator	Drug: PlaceboOral or Nasogastric tube (NG)
Sisunatovir	Active comparator	Drug: ActiveOral or NG tube

Who may qualify

Ages: 1 day to 60 months
Sex: All
Healthy volunteers: Not accepted
Age groups: Child

Key inclusion criteria (3 listed)

1 day to ≤60 months of age and weight ≥2.5 kg to ≤23 kg
Positive RSV diagnostic test, antigen or molecular test
Evidence of Lower Respiratory Tract Infection (LRTI)

Key exclusion criteria (5 listed)

Premature infants (gestational age less than 35 weeks) AND <1 year of post-natal age
Neonates with intrauterine growth restriction
Expected to receive an antiviral for another viral infection within 10 days of screening
Suspected or confirmed clinically significant moderate or severe bacterial infection that may interfere with the evaluation of response to the study intervention
Known to have significant comorbidities that would limit the ability to administer the study intervention or evaluate the safety or clinical response to the study intervention

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
PlaceboPlacebo	Drug	Placebo
ActiveAlso: PF-07923568, RV521Sisunatovir	Drug	Sisunatovir

Primary outcome

Number of Participants With Treatment Emergent Adverse Events (TEAEs)
Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
An adverse event (AE) was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs. All AEs were included for evaluation.
Number of Participants Who Discontinued From Study Due to TEAEs
Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs.
Number of Participants Who Discontinued From Study Due to Serious TEAEs
Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
An AE was any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs. A serious AE (SAE) was any untoward medical occurrence at any dose that: resulted in death; was life-threatening experience (immediate risk of death); required inpatient hospitalization or prolongation if existing hospitalization; resulted in persistent or significant disability/ incapacity; resulted in congenital anomaly/birth defect; other important event or situation as pre-specified in protocol.
Number of Participants With Clinically Significant Laboratory Abnormalities
Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
Following parameters were analyzed for laboratory examination: hematology (hemoglobin, hematocrit, red blood cell count, platelet count, white blood cell count, mean cell volume, mean cell hemoglobin \& concentration); chemistry: urea and creatinine, estimated glomerular filtration rate (eGFR), gamma-glutamyl transferase (GGT), calcium, sodium, potassium, chloride, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin, alkaline phosphatase, albumin, total protein, cystatin C; urinalysis: pH, glucose, protein, blood, ketones, nitrites, leukocyte esterase, albumin, creatinine (urine), urine albumin to creatinine ratio. Clinically significant laboratory abnormalities findings were based on investigator discretion.
Number of Participants With Clinically Significant Vital Signs
Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)
Vital signs included systolic and diastolic blood pressure, pulse rate/heart rate, temperature, respiratory rate, and oxygen saturation. Clinically significance vital signs findings were based on investigator discretion.

1 secondary outcome

Plasma Concentrations Versus Time Summary of Sisunatovir
Time frame: Day 3: Pre-dose, T1 and T2 hours post-dose; Day 5: Pre-dose; where T1 is the first analysis time point post-dose while T2 is the second analysis time point post-dose

Results and safety

Results posted to the registry on 30 Dec 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
Cohort 1A: Sisunatovir	1	1
Cohort 1A: Placebo	1	1
Cohort 1B: Sisunatovir	2	2
Cohort 1B: Placebo	1	1
Cohort 1C: Sisunatovir	3	3
Cohort 1C: Placebo	2	2

Primary outcome: Number of Participants With Treatment Emergent Adverse Events (TEAEs)

Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days). Count of participants. Unit: Participants

Measure	Cohort 1A: Sisunatovir n = 1	Cohort 1A: Placebo n = 1	Cohort 1B: Sisunatovir n = 2	Cohort 1B: Placebo n = 1	Cohort 1C: Sisunatovir n = 3	Cohort 1C: Placebo n = 2
Value	0	1	1	1	3	1

Population analysed: Safety population consisted of all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

Primary outcome: Number of Participants Who Discontinued From Study Due to TEAEs

Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days). Count of participants. Unit: Participants

Measure	Cohort 1A: Sisunatovir n = 1	Cohort 1A: Placebo n = 1	Cohort 1B: Sisunatovir n = 2	Cohort 1B: Placebo n = 1	Cohort 1C: Sisunatovir n = 3	Cohort 1C: Placebo n = 2
Value	0	0	0	0	0	0

Population analysed: Safety population consisted of all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

Primary outcome: Number of Participants Who Discontinued From Study Due to Serious TEAEs

Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days). Count of participants. Unit: Participants

Measure	Cohort 1A: Sisunatovir n = 1	Cohort 1A: Placebo n = 1	Cohort 1B: Sisunatovir n = 2	Cohort 1B: Placebo n = 1	Cohort 1C: Sisunatovir n = 3	Cohort 1C: Placebo n = 2
Value	0	0	0	0	0	0

Population analysed: Safety population consisted of all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

Primary outcome: Number of Participants With Clinically Significant Laboratory Abnormalities

Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days). Count of participants. Unit: Participants

Measure	Cohort 1A: Sisunatovir n = 1	Cohort 1A: Placebo n = 1	Cohort 1B: Sisunatovir n = 2	Cohort 1B: Placebo n = 1	Cohort 1C: Sisunatovir n = 3	Cohort 1C: Placebo n = 2
Value	0	0	0	0	0	0

Population analysed: Safety population consisted of all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

1 secondary outcome is reported in the full results.

Adverse events

Time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days). Other adverse events reported at 1% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Cohort 1A: Sisunatovir	0 of 1 (0%)	0 of 1 (0%)	0 of 1
Cohort 1A: Placebo	0 of 1 (0%)	1 of 1 (100%)	0 of 1
Cohort 1B: Sisunatovir	0 of 2 (0%)	1 of 2 (50%)	0 of 2
Cohort 1B: Placebo	0 of 1 (0%)	1 of 1 (100%)	0 of 1
Cohort 1C: Sisunatovir	0 of 3 (0%)	3 of 3 (100%)	0 of 3
Cohort 1C: Placebo	0 of 2 (0%)	1 of 2 (50%)	0 of 2

Limitations and caveats (from the sponsor): Sponsor decided to maintain company confidentiality, hence dose strengths, dose frequency, and PK sampling time points have not been disclosed in the record.

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 30 Dec 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 41673909Toussi SS, Calvo C, Haumann B, Thomas E, Franke RM, Kudela M, Zhang S, Banerjee A, Rees S, Shoji S, Welch H, Jordan I, Srisingh K, Daud M, Nemeth A, Rojo P, Toh TH, Ogunade I, Oku S, Amo K, Towner W, Newland J, Alami NN. Safety and Pharmacokinetics of the RSV Fusion Inhibitor Sisunatovir Across Two Early-phase Studies in Infants and Children With RSV Lower Respiratory Tract Infection. Pediatr Infect Dis J. 2026 Aug 1;45(8):724-732. doi: 10.1097/INF.0000000000005169. Epub 2026 Feb 12.
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.

Related trials for Respiratory Syncytial Virus Infections

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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

9 sites in 3 countries: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing Active in people with Respiratory Syncytial Virus Infections, run by Pfizer at 9 sites in 3 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 3 inclusion and 5 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: stopped early, as of the sponsor's last update on 30 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 9 sites in Japan, United States, South Africa. 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 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 30 Dec 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?

Number of Participants With Treatment Emergent Adverse Events (TEAEs) (time frame: From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)). 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 NCT06102174, which also lists 1 linked publication.

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 30 Dec 2025.