What is Beyfortus?

Official answer

by Drugs.com

Beyfortus is a long-acting monoclonal antibody with activity against the respiratory syncytial virus (RSV) that may be used to protect neonates and infants against lower respiratory tract disease (LRTD) caused by RSV. It was approved FDA-approved on July 17, 2023. Beyfortus has been available in the European Union since 31 October 2022.

What is Beyfortus used to treat?

Beyfortus is used to protect against RSV-caused lower respiratory tract infections in neonates and infants born during or entering their first RSV season. A single dose is given.

It may also be used to protect against RSV-caused lower respiratory tract infections in infants who remain vulnerable through their second RSV season such as those with congenital heart disease or chronic lung disease.

How does Beyfortus work?

The active ingredient in Beyfortus is nirsevimab which is a long-acting monoclonal antibody (mAB) that provides passive immunization against RSV to neonates and infants born during or entering their first RSV season and to infants with congenital heart disease or chronic lung disease entering their first or second RSV season.

Passive immunization is when antibodies are given to help prevent or fight certain infectious diseases. It helps protect immediately.

How is Beyfortus administered?

Beyfortus is given by intramuscular injection, preferably into the anterolateral aspect of the thigh. The gluteal muscle is not routinely used as an injection site because of the risk of damage to the sciatic nerve.

The dose is either 0.5mL or 1mL depending on the infant’s body weight.

Weight < 11lb (<5kg): 50mg given IM using a 0.5mL prefilled syringe.

Weight ≥ 11lb (≥5kg): 100mg given IM using a 1mL prefilled syringe.

There is limited data available for the use of Beyfortus in extremely preterm infants (gestational age <29 weeks, who are less than 8 weeks of age.

A single dose should be administered before the start of the RSV season, or from birth for infants born during the RSV season.

For infants undergoing cardiac surgery with cardiopulmonary bypass, an additional dose may be administered once the infant is stabilized after surgery, depending on the length of time passed:

< 90 days of the first dose, administer 50mg or 100mg depending on body weight

≥ 90 days since the first dose, administer a single dose of 50mg regardless of body weight.

What are the side effects of Beyfortus?

Beyfortus is generally well tolerated and the most common side effects reported include a mild-to-moderate rash (occurring in 0.7% of infants) occurring within 14 days postdose.

Other side effects that occurred in 0.3% to 0.5% of infants within 7 days postdose include fever and non-serious injection site reactions.

What are the ingredients in Beyfortus?

Active ingredients: Beyfortus contains nirsevimab and is available in two strengths:

50mg in 0.5 mL pre-filled syringe with purple plunger rod

100mg in 1 mL pre-filled syringe with light blue plunger rod.

Inactive ingredients: L-histidine, L-histidine hydrochloride, L-arginine hydrochloride, sucrose, polysorbate 80, water for injections.

Who makes Beyfortus?

Beyfortus was developed in partnership between Astra Zeneca and Sanofi.

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