Characteristics of Young Children Hospitalized With Acute Respiratory Failure From Infection With Respiratory Syncytial Virus, SARS-CoV-2, or Both, November 2023-March 2024

Background. Respiratory syncytial virus (RSV) and SARS-CoV-2 can cause acute respiratory failure in children. We compared characteristics and outcomes of children aged <2 years with respiratory failure from infection with RSV, SARS-CoV-2, or both viruses. Methods. We used data from a US pediatric respiratory virus hospitalization surveillance network including children with ICU admission for acute respiratory failure (receiving high-flow oxygen or mechanical ventilation) with RSV and/or SARS-CoV-2 during November 2023–March 2024. Demographic, clinical characteristics, and hospitalization outcomes were stratified by a positive test for RSV, SARS-CoV-2, or both viruses, and compared using chi-squared or Kruskal–Wallis tests. Multivariable analyses assessed independent associations between outcomes and infection. Results. Overall, 1406 children were included: 1253 (89.1%) for RSV, 105 (7.5%) for COVID-19, and 48 (3.4%) with RSV + SARS-CoV-2 detected. Children with RSV or RSV + SARS-CoV-2 had lower median ages (3.9 and 5.4 months, respectively) compared with those with SARS-CoV-2 (8.8 months; P < .001). Twenty percent of children with RSV and 43.8% with COVID-19 had an underlying medical condition. Among infants aged <1 year for whom preterm status was available, 31.5% with RSV and 50% with COVID-19 had either prematurity or a comorbidity. Children with SARS-CoV-2 were more likely to require invasive mechanical ventilation, receive vasoactive infusions, and die compared with RSV with and without SARS-CoV-2. Conclusions. Critically ill children <2 years of age infected with SARS-CoV-2 had more severe illness presentation and outcomes and were older compared with those with RSV and RSV + SARS-CoV-2 codetection. Most children were previously healthy, highlighting the need for prevention measures.