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FDA approves nirsevimab to prevent RSV in infants

July 17, 2023

The Food and Drug Administration (FDA) has approved a new product to protect infants and toddlers from respiratory syncytial virus (RSV).

The monoclonal antibody nirsevimab (brand name Beyfortus) was approved as a single injection for infants born during or entering their first RSV season and young children up to 24 months who remain at risk of severe disease in their second RSV season.

The Centers for Disease Control and Prevention’s (CDC’s) Advisory Committee on Immunization Practices (ACIP) will meet Aug. 3 to discuss whether to recommend nirsevimab and provide clinical guidance for its use.

“RSV can cause serious disease in infants and some children and results in a large number of emergency department and physician office visits each year,” John Farley, M.D., M.P.H., director of the Office of Infectious Diseases in the FDA’s Center for Drug Evaluation and Research said in a press release. “Today’s approval addresses the great need for products to help reduce the impact of RSV disease on children, families and the health care system.”

There are about 58,000 to 80,000 hospitalizations and 100 to 300 deaths per year in children under 5 years, according to CDC data. No vaccines are licensed in the U.S. to prevent RSV in children. Another monoclonal antibody, palivizumab, is available only for certain high-risk infants and young children.

In early June, an FDA advisory committee recommended approval of nirsevimab, an RSV F protein inhibitor monoclonal antibody developed by AstraZeneca in partnership with Sanofi.

Clinical trial data from term and late preterm infants show efficacy was about 75% against medically attended disease and 60% against hospitalization after five months, although the latter figure had broad confidence intervals that went below 0.

Safety of nirsevimab was studied in just over 3,000 infants and children, and no major safety concerns were seen. The most common adverse events reported were upper respiratory tract infection, fever and nasopharyngitis. The differences between the nirsevimab group and placebo group were small. Nirsevimab should not be given to infants and children with a history of serious hypersensitivity reactions to its active ingredients or any of its excipients, and caution should be used with infants and children who have clinically significant bleeding disorders. The product will have warnings and precautions about serious hypersensitivity reactions observed with other monoclonal antibodies.

Nirsevimab is classified as a drug, not a vaccine, and its rollout comes with questions around insurance coverage and whether it would be included in the immunization schedule, immunization registries and Vaccines for Children program. It also will be monitored in a separate FDA safety system from vaccines, and some states may restrict which health care providers can administer it. ACIP is likely to discuss these issues next month.

Another product to protect infants from RSV is also making its way through the regulatory process. In May, an FDA advisory committee voted in favor of RSVpreF, a vaccine that would be given to pregnant women. However, several committee members were concerned about preterm births. Approval of that vaccine is pending. Health officials have said most infants likely would not need protection from both RSVpreF and nirsevimab.




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