Neonatal Drug Therapy Manual

Nirsevimab

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Updated September 19, 2024 - 10:36am

Alternate Name(s): 
Beyfortus
Classification: 
Human Monoclonal Antibody; passive immunizing agent
Original Date: 
September 2024
Indications: 

The following are recommendations for Ontario patients. For other provinces, double check their provincial guidelines

 

  1. Prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants during their first RSV season. Infants should be offered Nirsevimab if:
  • The mother did not receive the RSV vaccine (Abrysvo®) during pregnancy. 
  • The mother’s RSV vaccination status is unknown.
  • The infant was born within 14 days of RSV vaccination.
  • The mother did receive the vaccine in appropriate timing, but the infant is deemed high-risk (consult provincial guidelines for eligibility)

 

2. Prevention for infants up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season. Qualifying criteria includes:

  • Chronic lung disease, hemodynamically significant congenital heart disease, immunocompromised states, down syndrome, cystic fibrosis, neuromuscular disease, congenital airway abnormalities. 
  • Consult provincial guidelines for more information 
Administration: 
  • IM
  • The 200 mg (2 mL) dose should be given as two separate 1 mL IM injections, in separate injection sites
Dosage: 

Dosing:

  • < 5kg: 50 mg (0.5 mL) IM once

  • > 5 kg: 100 mg (1 mL) IM once

Some infants will qualify for a second season, in which they will receive 200 mg (2 mL) IM once during that season

 

Timing (Ontario Guidelines. For other provinces, refer to their provincial guidelines):

  • Infants' First RSV season:
    • Infants born in 2024 prior to the RSV season should receive nirsevimab shortly before1 or during the RSV season 
    • If infants are born shortly before1 or during the RSV season should receive nirsevimab within the first week of birth2
  • For high risk infants who qualify for a second RSV season:
    • Should receive nirsevimab shortly before1 or during the RSV season 
Side Effects: 
  • Rash  
  • Fever 
  • Injection site reactions (redness, swelling, and pain) 
Reconstitution and Stability: 
  • Available as 50 mg and 100 mg pre-filled syringes
  • One time use
  • Refrigerate, protect from light. May be kept at room temperature (20℃ - 25℃) for a maximum of 8 hours. 
Compatibility: 
  • May be administered at same time as routine infant vaccines, though can be easier to monitor for side effects when given alone 
Notes: 

1nirsevimab has been shown to protect against severe RSV disease for at least 5 months, and the ideal timing of administration may differ depending on the clinical situation, timing of healthcare appointments, and local circulation of RSV. 

2Most infants born during the season will receive their immunization in the first week of life, however this can be delayed if critically unwell/admitted to intensive care. 

References: 
  • AstraZeneca Canada Inc. (2023). BEYFORTUS® Product Monograph. 
  • Ministry of Health. (2024). Respiratory Syncytial Virus (RSV) Prevention Program – Monoclonal antibody for infants and high-risk children. 
  • CDC-Frequently Asked Questions About RSV Immunization with Monoclonal Antibody for Children 19 Months and Younger, accessed Sept 2024. 

  • Respiratory syncytial virus (RSV) vaccines: Canadian Immunization Guide, accessed Sept 2024. 

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