Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract disease and hospitalization for respiratory illness among infants and young children. It causes annual epidemics worldwide and is responsible for more than 1,00,000 deaths in children under five years of age across the globe. According to a study published in the New England Journal of Medicine, the monoclonal antibody nirsevimab is effective in preventing hospitalization for RSV-associated lower respiratory tract infection among infants. The study showed that nirsevimab can prevent hospitalizations related to RSV in infants in real-world conditions. Nirsevimab is a monoclonal antibody against RSV, characterized by an extended in vivo half-life (3 times more than standard monoclonal antibody). It specifically targets the highly conserved epitope site Ø on the prefusion form of the RSV fusion (F) protein.
The randomized study conducted by Drysdale et al. involved infants aged 12 months or younger, who were born after at least 29 weeks of gestation and were entering their first RSV season in France, Germany, or the United Kingdom. The infants were randomly assigned in a 1:1 ratio to either receive a single intramuscular injection of nirsevimab or standard care before or during the RSV season. The study enrolled a total of 8,058 infants, with 4,037 receiving nirsevimab and 4,021 receiving standard care. Among these, 11 infants (0.3%) in the nirsevimab group and 60 (1.5%) in the standard care group were hospitalized for RSV-associated lower respiratory tract infections, indicating an 83.2% efficacy of nirsevimab (P <0.001). Very severe RSV-associated lower respiratory tract infections occurred in 5 infants (0.1%) in the nirsevimab group and 19 (0.5%) in the standard care group, indicating a nirsevimab efficacy of 75.7% (P=0.004). The efficacy of nirsevimab against hospitalization for RSV-associated lower respiratory tract infections was 89.6%.
In July 2023, the Food and Drug Administration (FDA) approved nirsevimab’s use in preventing RSV disease in newborns and infants. The Centers for Disease Control and Prevention (CDC) recommends its application for infants under 8 months during their initial RSV season and for high-risk 8 to 19-month-olds entering their second season. In a study conducted by Griffin et.al, it was found that a single injection of nirsevimab can result in fewer medically attended RSV-associated lower respiratory tract infections and hospitalizations than a placebo. This protection was observed throughout the RSV season in healthy preterm infants.
The study findings affirm that nirsevimab effectively shields infants from hospitalizations arising from severe cases of RSV-associated lower respiratory tract infections, with a minimal adverse event rate of 2.1%. Emphasizing the considerable impact of RSV on pediatric primary care during winter, the researchers highlight nirsevimab’s potential to alleviate this burden and enhance patient outcomes.
References
- Drysdale SB, Cathie K, Flamein F, Knuf M, Collins AM, Hill HC, et al. Nirsevimab for Prevention of Hospitalizations Due to RSV in Infants. New England Journal of Medicine. 2023 Dec 28;389(26):2425–35.
- Griffin MP, Yuan Y, Takas T, Domachowske JB, Madhi SA, Manzoni P, et al. Single-Dose Nirsevimab for Prevention of RSV in Preterm Infants. New England Journal of Medicine. 2020 Jul 30;383(5):415–25.