Respiratory Syncytial Virus Immunization Coverage Among Infants Through Receipt of Nirsevimab Monoclonal Antibody or Maternal Vaccination - United States, October 2023-March 2024.

Respiratory syncytial virus (RSV) is the leading cause of infant hospitalization in the United States. A new RSV monoclonal antibody (nirsevimab) for infants and an RSV vaccine for pregnant women were recommended by the Advisory Committee on Immunization Practices in August and September 2023, respectively, to protect infants against RSV infection. Sufficient data have become available to allow estimates of infant RSV immunization coverage through administration of these products. Among infants born during October 2023-March 2024, infant RSV immunization coverage was estimated by summing the total number of infants who received nirsevimab and the number of women of childbearing age who received RSV vaccine, as reported to immunization information systems (IISs) in 33 U.S. states and the District of Columbia (DC), and dividing by the total number of live births, obtained from CDC Wide-ranging Online Data for Epidemiologic Research (WONDER) natality data. Across 33 states and DC, an estimated 29% of infants born during October 2023-March 2024 were immunized against RSV during the 2023-24 respiratory virus season, including 19% through infant receipt of nirsevimab and 10% through maternal RSV vaccination. Infant RSV immunization coverage through nirsevimab or maternal vaccination ranged from an estimated 11% to 53% by state. Among infants who received nirsevimab, 38% received it within the first week of life (0-6 days after birth). Continued efforts are needed to increase RSV immunization coverage among infants and pregnant women.