In the Journals: Nirsevimab

Respiratory syncytial virus (RSV) is one of the most common causes of hospitalization in young children. Every year in the United States, RSV accounts for about:

• 1.5 million outpatient visits
• 500,000 emergency department visits
• 80,000 hospitalizations
• 100-300 deaths

Most hospitalizations and deaths occur in children less than 3 months of age.

Now, however, we have tools to prevent this infection in young children. In addition to maternal immunization with the RSV fusion protein, a long-acting monoclonal antibody preparation called nirsevimab, which is also targeted to the RSV fusion protein, is available. Although supply shortages have limited its availability this season, the product should be widely available next season. Nirsevimab is currently recommended to be given to all babies less than 8 months of age during RSV season, specifically between September and January.

On Dec. 28, 2023, researchers from the United Kingdom published the results of a prospective, placebo-controlled trial in 8,058 healthy infants that had served as the basis for licensure (Drysdale SB, Cathie K, Flamein F, et al. Nirsevimab for Prevention of Hospitalizations Due to RSV in Infants. New Engl J Med 2023 Dec 28;389:(26):2425-2435). Eleven infants (0.3%) in the nirsevimab group were hospitalized with severe RSV-associated lower respiratory tract infection compared with 60 (1.5%) in the placebo group for an efficacy of 83.2%. Very severe lower respiratory infection, defined as a hospitalization requiring supplemental oxygen, occurred in five infants (0.1%) in the nirsevimab group and 19 (0.5%) in the placebo group for an efficacy of 75.7%.

The availability of a product to prevent a disease as devastating as RSV should be a welcome relief to both physicians and families.