Nirsevimab
Nirsevimab (BEYFORTUS) is a long-acting monoclonal antibody designed to prevent severe Respiratory Syncytial Virus (RSV) disease in infants and young children. It is administered as a single intramuscular injection and provides protection throughout the typical RSV season (approximately 5 months). This medication is specifically indicated for infants born during or entering their first RSV season, as well as children up to 24 months who remain at high risk for severe RSV disease during their second season.
Nirsevimab is a preventive monoclonal antibody that protects infants and high-risk young children from severe RSV lung infections with a single injection.
Key facts at a glance
- ATC
- J06BD08
- RxNorm
- 2642401
- Generic
- Nirsevimab
- Class
- atc-j06
- Brands
- Beyfortus
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- prefilled syringe
- 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.
Dosage and administration
- Usual dose
- not indicated for routine adult use
- Maximum
- consult physician
- Frequency
- single dose
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 50mg for weight <5kg; 100mg for weight ≥5kg
- Maximum
- consult physician
- Frequency
- single dose
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- not indicated for routine geriatric use
- Maximum
- consult physician
- Frequency
- single dose
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
5 groupspediatric_age
infants 0 12 monthssingle dose based on weight
recommended for prevention of RSV in infants during their first RSV season
observe for hypersensitivity reactions
geriatric
elderly 65 plussingle dose as recommended
approved for use in adults 60 years and older at higher risk for RSV
monitor for adverse reactions
renal_impairment
mild to moderateno adjustment needed
no dose adjustment required for mild to moderate renal impairment
standard monitoring
hepatic_impairment
mild to moderateno adjustment needed
no dose adjustment required for mild to moderate hepatic impairment
standard monitoring
lactation
breastfeedingno adjustment needed
transfer to breast milk is expected to be minimal; continue as directed
monitor infant for any adverse effects
Use with caution and monitor for adverse effects.
Statistics and clinical data
FDA approval year
First FDA approval date for nirsevimab (Beyfortus)
Drug class
Therapeutic classification of nirsevimab
Indication
Primary therapeutic indication for nirsevimab
Route of administration
Method of drug administration
Prevention of RSV lower respiratory tract disease in: (1) infants born during or entering their first RSV season, and (2) children up to 24 months of age who remain at increased risk for severe RSV disease during their second RSV season.
Nirsevimab is a recombinant human IgG1 monoclonal antibody that binds to the prefusion conformation of the RSV fusion (F) protein, preventing viral entry into host cells and subsequent RSV infection.
Administered as a single intramuscular injection. Can be given concurrently with routine childhood vaccines at different injection sites. Potential for hypersensitivity reactions exists. Should not be administered to individuals with known severe hypersensitivity to the active substance or any excipients.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
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 July 26, 2026. · Read our editorial policy