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Nirsevimab

Phase 4

RSV Immunization | Monoclonal antibody | Infectious Disease |Sanofi|Trials Updated: Oct 9, 2025

Nirsevimab development status

Highest phase Phase 4 (NCT07109297)
Phase scored for SNYPhase 3
Registered trials 8 across 3 sponsors since Jul 2020

Success Probability

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Market & Valuation

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Trial Design

RandomizedNO_TREATMENT_CONTROLLED
Total Trials1
Total Enrollment8,057

FDA Designations

No designations recorded

Nirsevimab clinical trials

Nirsevimab · 1 trial · 2 indications

Phase 3 1
NCT05437510Study of a Single Intramuscular Dose of Nirsevimab in the Prevention of Hospitalizations Due to Respiratory Syncytial Virus (RSV) Infection in Healthy Term and Preterm Infants During the First Year of LifeRSV Immunization
COMPLETED8,057 Analytics
PHASE3COMPLETED
Study of a Single Intramuscular Dose of Nirsevimab in the Prevention of Hospitalizations Due to Respiratory Syncytial Virus (RSV) Infection in Healthy Term and Preterm Infants During the First Year of Life
RSV ImmunizationUnlock trial analytics

Study Endpoints

Primary Endpoints

Number of Participants With Respiratory Syncytial Virus (RSV) Lower Respiratory Tract Infection (LRTI) Hospitalization Through the Respiratory Syncytial Virus Season
From dosing/randomization (Day 1) up to approximately 7 months

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: \<2 months, ≥60 breaths per minute (/min); 2 to 6 months, ≥50 breaths/min; \>6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation \<95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. RSV season was the period of increased RSV infection.

Secondary Endpoints

Number of Participants With Very Severe Respiratory Syncytial Virus Lower Respiratory Tract Infection Through the Respiratory Syncytial Virus Season
From dosing/randomization (Day 1) up to approximately 7 months
Number of Participants With Respiratory Syncytial Virus Lower Respiratory Tract Infection Hospitalization Through the Respiratory Syncytial Virus Season in Each Country
From dosing/randomization (Day 1) up to approximately 7 months
Number of Participants With Hospitalization for All-Cause Lower Respiratory Tract Infection Through the Respiratory Syncytial Virus Season
From dosing/randomization (Day 1) up to approximately 7 months
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposePREVENTION

Treatment Arms

ArmTypeDescription
NirsevimabEXPERIMENTAL1 intramuscular injection at Day 01
No preventive intervention for RSVNO_INTERVENTIONNo intervention

Interventions

NameTypeDescription
NirsevimabBIOLOGICALPharmaceutical Form: Solution for Injection Route of Administration: Intramuscular
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Eligibility Criteria

Age Range0 Days to 12 Months
SexALL
Healthy VolunteersYes
Study Sites240

Inclusion Criteria: * Born at ≥ 29 weeks gestational age and aged 0 to 12 months (calendar age), who entered their first RSV season on the day of inclusion in the study (D01) * Informed consent form was signed and dated by the parent(s) or other LAR(s) (and by an independent witness if required by ...

Countries:FranceGermanyUnited Kingdom
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Frequently asked questions about Nirsevimab

What is nirsevimab used for?

Nirsevimab is used for RSV immunization, specifically to prevent hospitalizations caused by respiratory syncytial virus infection in healthy term and preterm infants during their first year of life. It is a monoclonal antibody given as a single intramuscular dose and is being developed by Sanofi.

Who makes nirsevimab?

Nirsevimab is developed by Sanofi, which trades on the New York Stock Exchange under the ticker SNY. Sanofi is the company listed as the developer of the asset in its clinical program for RSV immunization in infants.

What phase is nirsevimab in?

Nirsevimab is in Phase 3 clinical development. It is an investigational monoclonal antibody and is not described as approved. Its Phase 3 program has been completed, with one completed trial and no active trials currently listed.

What clinical trials is nirsevimab in?

Nirsevimab has been studied in the Phase 3 trial NCT05437510, titled a study of a single intramuscular dose of nirsevimab in the prevention of hospitalizations due to respiratory syncytial virus infection in healthy term and preterm infants during the first year of life. That trial is completed and enrolled 8,057 participants across France, Germany, and the United Kingdom.

How was the nirsevimab Phase 3 trial designed?

The Phase 3 trial NCT05437510 was a randomized study with a no-treatment control and enrolled 8,057 healthy infant volunteers, including term and preterm infants, with ages starting at 0 days and both sexes eligible. It was not double blinded and was not biomarker selected.