Clinical Outcomes in Children <5 Years of Age Hospitalized for Respiratory Syncytial Virus, COVID-19 or Influenza in the United States.

Background: This study aimed to compare the clinical burden among young children hospitalized for respiratory syncytial virus (RSV) to coronavirus disease 2019 (COVID-19) or influenza.

Methods: Patients <5 years of age hospitalized for RSV, COVID-19 or influenza between September 2022-August 2024 were selected from the PINC-AI Healthcare Database for retrospective cohort analysis. Hospitalization outcomes included length of stay, supplemental oxygen use, intensive care unit (ICU) admission, invasive mechanical ventilation (IMV) and inhospital death. Weighted robust Poisson regression models estimated risk ratios with 95% confidence intervals comparing RSV to COVID-19 and influenza, with further stratification by age at admission (<1, 1 and 2-4 years).

Results: Among 56,634 children (43,766 RSV; 6,697 COVID-19; 6,171 influenza) hospitalized for the acute respiratory infections, children hospitalized for RSV were mean age 0.7 years, versus 0.7 (COVID-19) and 1.7 years (influenza), more often admitted to the ICU (28.2%, vs. 22.4% and 21.7%), required supplemental oxygen (46.1%, vs. 20.2% and 26.2%) and IMV (12.0%, vs. 8.3% and 8.2%). In adjusted regression models, increased risks of supplemental oxygen, ICU admission and IMV persisted with RSV as compared with COVID-19 and influenza. Risks with RSV were highest among children <1 year old. Inpatient mortality was observed [0.1% (RSV), 0.3% (COVID-19), 0.4% (influenza)].

Conclusions: Viral respiratory diseases cause a significant burden of illness in hospitalized children <5 years of age. Compared with COVID-19 and influenza, RSV had a significantly higher risk of nearly all inhospital outcomes examined. Inhospital mortality for COVID-19 and influenza was higher than RSV.