Characteristics of Children Aged 0 to 23 Months Hospitalized With Respiratory Syncytial Virus.

BACKGROUND AND OBJECTIVES Respiratory syncytial virus (RSV) is a leading cause of hospitalization among young children. Nirsevimab is recommended for all infants younger than 8 months and children aged 8 to 19 months who are at increased risk of severe RSV entering their second RSV season. Additional data are necessary to identify children aged 8 to 19 months at increased risk for severe disease. METHODS The Respiratory Syncytial Virus Hospitalization Surveillance Network, a population-based surveillance system, captures laboratory-confirmed RSV-associated hospitalizations in 12 states. We compared demographics and clinical characteristics of children aged 0 to 23 months by age category, and of children aged 12 to 23 months by severity (not admitted to the intensive care unit [ICU], admitted to the ICU, or with prolonged [≥3 days] ICU admission) during the 2022-2023 season using χ2 tests and logistic regression. RESULTS Among 3659 randomly sampled hospitalized children in 2022-2023, 31.2%, 40.0%, and 28.9% were aged 0 to 2, 3 to 11, and 12 to 23 months, respectively. Compared with children aged 0 to 2 months, children 3 to 11 and 12 to 23 months were more likely to have at least 1 underlying medical condition (UMC) (3.4%, 12.6%, 23.4%, respectively; P < .05). Children aged 12 to 23 months with prolonged ICU admission were more likely to have airway abnormalities, cardiovascular disease (CVD), Down syndrome (with or without concomitant CVD), and feeding tube dependence than those without ICU admission (P < .05 for all). CONCLUSIONS UMCs were more frequently identified among hospitalized children aged 12 to 23 months compared with children 0 to 2 months; prolonged ICU admission was associated with airway abnormalities, CVD, Down syndrome, and feeding tube dependence.