New FDA-Approved Medication to Prevent RSV-Infections

On July 17, 2023, the FDA announced approval of BeyfortusTM (nirsevimab) for prevention of respiratory syncytial virus (RSV) infections. Nirsevimab is a monoclonal antibody delivered intramuscularly as a single-dose that demonstrated 70-75% efficacy at reducing medically attended RSV lower respiratory tract infections for preterm and term infants in clinical trials1,2. Nirsevimab is classified as a drug by the FDA and is not a vaccine. Despite this designation, the Advisory Committee on Immunization Practices (ACIP) unanimously recommended the addition of nirsevimab to the Centers for Disease Control and Prevention’s (CDC’s) child immunization schedule and Vaccines for Children (VFC) program on August 3rd, 2023.

The CDC recommends one dose of nirsevimab:

  • For all infants younger than 8 months, born during or entering their first RSV season
  • For children 8 to 19 months old who are at increased risk for severe RSV disease during their 2nd RSV season
Key Details of Nirsevimab
(From Beyfortus™ package insert)
Mechanism of Action Nirsevimab is a monoclonal antibody that binds to a receptor, specific to the surface of RSV, and prevents the virus from attaching to, and infecting the host’s cell.
Duration of Action Nirsevimab is active for at least 5 months and therefore only needs to be administered once per RSV season. A modification to the monoclonal antibody prolongs the time to degradation in the body.
Dosage

Born during or entering their first RSV season

  • 50 mg by IM injection if < 5 kg body weight
  • 100 mg by IM injection if ≥ 5 kg body weight

Children at increased risk in their second RSV season

  • 200 mg IM
Dose Timing
  • At birth if born during RSV season*
  • At the start of RSV season if it’s the patient’s first RSV season
  • At the start of the second RSV season for selected high-risk patients
How Supplied / Storage

Supplied as:

  • 50 mg/0.5 mL single-dose pre-filled syringe
  • 100 mg/mL single-dose pre-filled syringe

Storage:

  • Store refrigerated from 36°F to 46°F. After removal from the refrigerator, nirsevimab must be used within 8 hours or discarded.
Most Common Adverse Reactions
  • Rash (0.9%)
  • Injection site reactions (0.3%)
*RSV season is the time of year when RSV infections are most common. Typically, in Ohio, this is from November to March.
  1. Griffin, M. P., et al. (2020). “Single-Dose Nirsevimab for Prevention of RSV in Preterm Infants.” New England Journal of Medicine 383(5): 415-425.
  2. Hammitt, L. L., et al. (2022). “Nirsevimab for Prevention of RSV in Healthy Late-Preterm and Term Infants.” New England Journal of Medicine 386(9): 837-846.
RSV Resources
Access More Provider, Patient and Family Resources for Preventing RSV