FDA advisers endorse antibody to protect against RSV in infants and some young toddlers

By Jamie Gumbrecht, CNN

(CNN) — Advisers to the US Food and Drug Administration voted Thursday to endorse a monoclonal antibody designed to protect infants and some young toddlers from RSV.

Members of the agency’s Antimicrobial Drugs Advisory Committee voted 21-0 that the benefit-risk profile of nirsevimab was favorable in infants and 19-2 that it was favorable in children up to 24 months who are vulnerable to severe respiratory syncytial virus.

Next, the FDA will consider the advice of the advisers and decide whether to approve the treatment.

The monoclonal antibody, nirsevimab, was developed by AstraZeneca and Sanofi. It’s designed to be given to infants in a single shot at birth or just before the start of a baby’s first RSV season, or as a larger dose in a second RSV season in children who are highly vulnerable.

If approved, it will be the first single-dose preventative treatment for all infants against RSV. Unlike with a vaccine, with which the body builds up its immunity in reaction over time, a monoclonal antibody works right away.

In trials, nirsevimab reduced the risk of RSV-linked lower respiratory tract infections that needed medical attention by about 75% and RSV-related hospitalization by about 78% when compared with a placebo. No major safety concerns were identified; some common side effects were rash and injection-site reactions.

Another monoclonal antibody treatment approved in the US and Europe, palivizumab, or Synagis, protects against infection in high-risk infants. With that treatment, infants get an intramuscular injection every month during RSV season, and it usually requires five doses.

Last month, the FDA’s vaccine advisers voted in support of a new vaccine to prevent RSV in infants.That maternal vaccine is a single-dose shot that would be given to a pregnant people late in pregnancy, triggering the development of antibodies that are passed on to the fetus and providing protection for about the first six months of a baby’s life. Trials show that the vaccine, made by Pfizer, cuts the risk that infants would need to see a doctor or be admitted to the hospital with a moderate to severe infection.

Nearly every child gets RSV before the age of 2, according to the US Centers for Disease Control and Prevention, but last winter, the virus overwhelmed pediatric hospitals all across the United States. Although it’s often a milder respiratory infection for children and most adults, studies show that it is still a leading cause of hospitalization among infants.

Globally, in 2019 alone, there were 33 million cases and more than 3.6 million hospitalizations. It’s estimated that there were 26,300 in-hospital RSV deaths of children younger than 5 and 101,400 deaths overall, according to a 2022 study published in the Lancet.

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