Recommendation for use of a long-acting monoclonal antibody to prevent respiratory syncytial virus infection in infants and young children.

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infections (LRTIs) in infants and young children. In April 2024, the Korea Ministry of Food and Drug Safety approved nirsevimab (Beyfortus), a long-acting monoclonal antibody, as a passive immunization to prevent RSV-associated LRTI among infants and young children. Nirsevimab was launched in Korea in February 2025. This report summarizes the recommendations of the Committee on Infectious Diseases of the Korean Pediatric Society regarding the use of nirsevimab. We recommend a single dose of nirsevimab for all neonates born during the RSV season (October to March), as well as all infants younger than 6 months at the start of the RSV season (i.e., those born between April and September of that year). Nirsevimab should be administered shortly after birth (within the first week of life) to neonates born during the RSV season and just before or early in the season (late September to October) to infants entering their first RSV season. Nirsevimab may also be considered for children younger than 2 years of age who are at increased risk of severe RSV disease and entering their second RSV season.