The US Food and Drug Administration (FDA) has approved Beyfortus (nirsevimab-alip) as a preventive treatment for Respiratory Syncytial Virus (RSV) lower respiratory tract disease. This approval applies to neonates and infants born or entering their first RSV season, as well as children up to 24 months of age who are vulnerable to severe RSV disease through their second RSV season. RSV is a virus that causes acute respiratory infection, with infants and young children being particularly susceptible to developing lower respiratory tract diseases such as pneumonia and bronchiolitis. Premature infants and those with chronic lung or heart conditions are at a higher risk of severe RSV disease.
Beyfortus is a monoclonal antibody that works against RSV. Monoclonal antibodies are lab-made proteins that imitate the immune system’s ability to fight off viruses. Administration of Beyfortus as a single intramuscular injection before or during the RSV season can provide protection throughout the season.
The FDA approval was based on three clinical trials (Trials 03, 04, and 05), with the primary measure of efficacy being the incidence of medically attended RSV lower respiratory tract infection (MA RSV LRTI). Trials 03 and 04 were randomized, double-blind, placebo-controlled trials involving preterm and term infants.
In Trial 03, 25 out of 969 preterm infants who received Beyfortus (2.6%) experienced MA RSV LRTI, compared to 46 out of 484 infants who received the placebo (9.5%). This represented a reduction in the risk of MA RSV LRTI by around 70% compared to the placebo.
In Trial 04, 12 out of 994 term and late preterm infants who received Beyfortus (1.2%) experienced MA RSV LRTI, while 25 out of 496 infants who received the placebo (5.0%) developed the infection. Beyfortus reduced the risk of MA RSV LRTI by approximately 75% compared to the placebo.
Trial 05, a randomized, double-blind, active-controlled trial, supported the use of Beyfortus in children up to 24 months of age who remain vulnerable to severe RSV disease throughout their second RSV season. The trial included preterm infants and infants with chronic lung or congenital heart disease. The safety and pharmacokinetic data from Trial 05 provided evidence for using Beyfortus to prevent MA RSV LRTI in this population.
Possible side effects of Beyfortus include rash and injection site reactions. It is not recommended for use in infants and children with a history of serious hypersensitivity reactions to Beyfortus or its ingredients.
Beyfortus received Fast Track designation from the FDA for this indication.
The FDA granted approval for Beyfortus to AstraZeneca.
About the FDA:
The FDA is a US government agency responsible for ensuring the safety, effectiveness, and security of human and veterinary drugs, vaccines, and other biological products, as well as medical devices. The agency also oversees the safety and security of the nation’s food supply, cosmetics, dietary supplements, and tobacco products.
