News Brief: Nirsevimab for Prevention of Respiratory Syncytial Virus (RSV) Lower Respiratory Tract Disease in Infants and Children Up to 24 Months of Age

In 2023, the Food and Drug Administration approved nirsevimab (BEYFORTUS), a respiratory syncytial virus (RSV)-preventive antibody, which the Centers for Disease Control and Prevention (CDC) has recommended for some infants and young children.[1],[2] The antibody targets the prefusion (before attacking the cell) form of a surface protein of the RSV virus and is delivered via a single intramuscular injection. The approval was primarily based on data from two randomized clinical trials, one of 1,453 infants and the other of 1,490 infants. Both trials were placebo-controlled; infants born prematurely and at term were included.

Both trials found that nirsevimab protected infants and toddlers from RSV lower respiratory tract disease for at least 150 days. Jointly, these studies found that 2% of infants receiving nirsevimab had RSV severe enough to require medical attention, compared with 7% of those receiving placebo. Across both studies, about 1% of infants had adverse reactions, which were mostly mild to moderate in severity.

The CDC recommends that neonates and infants born during or entering their first RSV season (fall through spring) receive a single dose of nirsevimab within one week after birth.[3] Most newborns whose mothers received the RSV vaccine during pregnancy do not need nirsevimab.[4] Infants born outside of the RSV season and who are younger than eight months as they enter their first RSV season should receive a single dose shortly before the season begins but may receive a dose at any time during the season.

The CDC further recommends that older infants and toddlers (nine to 19 months) be considered for nirsevimab if they are at increased risk of severe RSV disease.

In October 2023, the CDC issued a nirsevimab shortage alert for the 2023-2024 RSV season and recommended that the drug be prioritized for infants younger than six months of age who were born prematurely (<29 weeks) or infants who otherwise have significant immune, heart, lung or neuromuscular conditions that place them at increased risk of lower respiratory infection.[5] In January 2024, after the manufacturer released additional doses, the CDC advised clinicians to return to the original recommendations on use of nirsevimab in young children.[6]
 

References

[1] U.S. Food and Drug Administration News Release. FDA approves new drug to prevent RSV in babies and toddlers. July 17, 2023. https://www.fda.gov/news-events/press-announcements/fda-approves-new-drug-prevent-rsv-babies-and-toddlers. Accessed November 9, 2023.

[2] AstraZeneca. Label: nirsevimab-alip (BEYFORTUS). July 2023. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/761328s000lbl.pdf. Accessed November 9, 2023. [p.1 under indication]

[3] U.S. Center for Disease Control and Prevention. Respiratory syncytial virus infection (RSV). August 4, 2023. https://www.cdc.gov/rsv/clinical/index.html#immunizations-protect-infants. Accessed November 9, 2023.

[4] Fleming-Dutra KE, Jones JM, Roper LE, et al. Use of the Pfizer respiratory syncytial virus vaccine during pregnancy for the prevention of respiratory syncytial virus-associated lower respiratory tract disease in infants: recommendations of the Advisory Committee on Immunization Practices - United States, 2023. MMWR Morb Mortal Wkly Rep. 2023;72(41):1115-1122.

[5] CDC Health Alert Network. Limited Availability of Nirsevimab in the United States—Interim CDC Recommendations to Protect Infants from Respiratory Syncytial Virus (RSV) during the 2023–2024 Respiratory Virus Season. October 23, 2023.

[6] U.S. Center for Disease Control and Prevention. Updated guidance for healthcare providers on Increased supply of nirsevimab to protect young children from severe respiratory syncytial virus (RSV) during the 2023–2024 respiratory virus season. January 5, 2024. https://emergency.cdc.gov/newsletters/coca/2024/010524a.html. Accessed February 28, 2024.