Beyfortus® injection

Beyfortus® injection

This product is manufactured by Sanofi Pasteur using the ingredient nirsevimab.

This product is taken via intramuscular injection.

Why is it prescribed?

Nirsevimab is used for the prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in infants and children at high risk of RSV disease.

  • Respiratory syncytial virus (RSV) causes respiratory illness that can cause symptoms ranging from mild to severe (requiring hospitalization).
  • Nirsevimab protects your baby from severe RSV disease
    • Nirsevimab is generally given to babies at birth prior to discharge from the hospital.
    • Children who continue to be at risk of severe RSV disease into their 2nd RSV season may receive another dose.
  • The dose protects most babies from severe RSV for at least 6 months.
  • Nirsevimab is administered by a healthcare provider as an injection into the muscle, usually the outer part of the thigh.

Alternatives

See other products used in the treatment of •

Dose at birth

  • < 5 kg: 50 mg
  • ≥ 5 kg: 100 mg

Dose for children who remain vulnerable to severe respiratory syncytial virus (RSV) disease entering their second RSV season:

  • 200 mg, given as 2x 100 mg

Nirsevimab provides antibodies to your child that block the respiratory syncytial virus from entering human cells and causing illness.  Unlike vaccines, where the child’s immune system produces the antibodies, nirsevimab provides antibodies directly so it starts working right away.


  • rash
  • reaction where the needle was place (e.g., redness, swelling, pain)
  • fever
  • allergic reactions are possible

  • Do not use if your child is allergic to any of the ingredients.
  • If your child has conditions like nephrotic syndrome or chronic liver disease, the level of protection of nirsevimab may be reduced.

Drug Interactions

  • None known.