Nirsevimab
Beyfortus (nirsevimab) is a long-acting monoclonal antibody designed to prevent severe Respiratory Syncytial Virus (RSV) lower respiratory tract disease in infants and young children at high risk for complications. It provides passive immunity by delivering ready-made antibodies against RSV, offering protection during the RSV season without requiring the immune system to develop its own response.
Beyfortus is a monoclonal antibody injection that prevents severe RSV disease in infants and high-risk young children during their first or second RSV season.
Key facts at a glance
- RxNorm
- 2642408
- Generic
- Beyfortus
- Class
- brand-name
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Prevention of RSV lower respiratory tract disease in neonates, infants, and children up to 24 months of age who are at increased risk for severe RSV disease during their first or second RSV season.
As a monoclonal antibody, Beyfortus provides passive immunity against RSV by binding to the fusion (F) protein on the RSV surface, preventing the virus from entering and infecting respiratory cells.
Administered as a single intramuscular injection at the beginning of or during RSV season, providing protection for approximately 5 months. Unlike vaccines, it does not require the immune system to generate its own response. Common adverse reactions may include rash and injection site reactions.
Official drug label
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This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed September 3, 2026. · Read our editorial policy