RSV wasn’t as hard on U.S. babies last winter. This may be why

Last winter’s respiratory syncytial virus, or RSV, season wasn’t as brutal for U.S. babies. A new study suggests two preventive tools — a maternal vaccine and a monoclonal antibody for infants — may have helped.

The 2024-25 RSV season was the first in which the vaccine and the monoclonal antibody, which can prevent severe RSV lung infections in babies, were widely available. A study of two hospital surveillance systems found that RSV hospitalization rates last winter for…