News Health & Medicine RSV wasn’t as hard on U.S. babies last winter. This may be why It was the first RSV season a maternal vaccine and a monoclonal antibody were widely available A hospitalized infant receives treatment for bronchiolitis, a lung infection most commonly caused by respiratory syncytial virus, or RSV. In the first RSV season that a maternal vaccine and a monoclonal antibody to prevent severe RSV lung infections in babies were widely available, RSV hospitalization rates for infants up to 7 months old dropped, compared with earlier seasons. BSIP SA/Alamy Stock Photo By Aimee Cunningham 1 hour ago 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 babies up to 7 months old were lower than in two combined RSV seasons prior to the COVID-19 pandemic, researchers report May 8 in Morbidity and Mortality Weekly Report. Those earlier RSV seasons were the most recent that were typical — meaning not altered by the COVID-19 pandemic — without the RSV preventive tools. Sign up for our newsletter We summarize the week's scientific breakthroughs every Thursday.