Infant Respiratory Syncytial Virus Immunization Coverage in the Vaccine Safety Datalink: 2023-2024.

BACKGROUND AND OBJECTIVES In 2023, the Advisory Committee on Immunization Practices recommended either Abrysvo, a vaccine administered during pregnancy, or nirsevimab, a monoclonal antibody administered to infants after birth, to protect infants from respiratory syncytial virus (RSV). Our objective was to assess the proportion of infants immunized against RSV through antenatal RSV vaccination or receipt of nirsevimab among linked pregnancy-infant dyads. METHODS Using data from 10 Vaccine Safety Datalink health systems and a validated algorithm, we identified pregnant women aged 12 to 55 years with a live birth of 32 weeks' gestation or more from September 22, 2023, through March 31, 2024. We identified RSV vaccination using electronic health records supplemented with immunization information system (registry) data. Among infants from eligible pregnancies, we identified nirsevimab administered through March 31, 2024. We assessed infant RSV immunization, defined as exposure to antenatal RSV vaccination or receipt of nirsevimab, stratified by race and ethnicity, age, and birth month. RESULTS A total of 36 949 eligible infants were included from 43 722 pregnancies. Overall, 72% of infants were immunized against RSV; estimates were highest among infants born to non-Hispanic (NH) Asian mothers (84%). Disparities were identified by race, with 60% coverage among infants born to NH Black or NH Middle Eastern or North African mothers. Coverage was 59% to 78% by birth month, with nirsevimab more commonly administered to infants born earlier in the season. CONCLUSIONS In this population of infants, 72% were immunized against RSV. Although overall coverage was high, disparities in immunization by race and ethnicity are a call to action.