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Nirsevimab

Phase 3

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

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

Clinical trial landscape

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 a monoclonal antibody used for RSV immunization, specifically to prevent hospitalizations due to respiratory syncytial virus (RSV) infection in healthy term and preterm infants during their first year of life. It is administered as a single intramuscular dose.

Who makes Nirsevimab?

Nirsevimab is developed by Sanofi, a biopharmaceutical company traded on the stock exchange under the ticker SNY. The drug is currently in Phase 3 clinical development for RSV immunization.

What phase is Nirsevimab in?

Nirsevimab is in Phase 3 clinical development. It is an investigational drug and has not been approved by regulatory authorities. A Phase 3 trial has been completed, evaluating its efficacy in preventing RSV-related hospitalizations in infants.

What clinical trials is Nirsevimab in?

Nirsevimab has one completed Phase 3 trial, identified as NCT05437510. This study enrolled 8,057 participants and evaluated a single intramuscular dose of Nirsevimab for preventing hospitalizations due to RSV infection in healthy term and preterm infants during their first year of life.

Is Nirsevimab a vaccine or an antibody?

Nirsevimab is a monoclonal antibody, not a vaccine. It is designed to provide passive immunization against respiratory syncytial virus (RSV) in infants, helping to prevent severe RSV infection that could lead to hospitalization.

What is the mechanism of action of Nirsevimab?

Nirsevimab is a monoclonal antibody that targets the respiratory syncytial virus (RSV). It works by binding to the virus to neutralize it, thereby preventing RSV infection and reducing the risk of hospitalization in infants during their first year of life.