(308) The 2022-23 National RSV Surge: An Epidemiologic Shift in Pediatric RSV Hospitalizations

Introduction: Pediatric hospitalizations for RSV bronchiolitis dramatically decreased globally during the COVID-19 pandemic. Regional U.S. data suggested a resurgence of pediatric RSV admissions in 2022-23 after lifting pandemic precautions, but national data are lacking. In this study we examined demographics, illness severity, and clinical outcomes of children hospitalized nationally with RSV bronchiolitis before, during, and after the COVID-19 pandemic.

Methods: A retrospective cohort analysis of the Pediatric Health Information System (PHIS) database from 48 U.S. pediatric hospitals was performed. Patients ages 0 days to < 5 years old presenting to the hospital with RSV bronchiolitis were identified using ICD-10 codes (J20.5; J21.0; J12.1; B97.4). 293,677 RSV+ patients were identified during the study period July 1, 2017 to June 30, 2023. RSV seasons were defined from July 1 to June 30 each year. Significance was determined using Kruskal-Wallis or Cochran-Armitage Chi-square test for trend.

Results: In the 2022-23 post-pandemic RSV surge, 96,716 RSV+ children presented to the hospital, a 2.4-fold increase from pre-pandemic seasons (2017-2020 annual average: 40,200; p< 0.001) with a 40% increase in ICU admissions (13,688 vs. 9,741; p< 0.001). RSV+ children in the 2022-23 surge were significantly older (median 11.4 months) than in pre-pandemic seasons (median 6.8 months; p< 0.001) and a lower proportion required hospital admission (53% vs. 68.5% pre-pandemic; p< 0.001) or ICU care (33.8% vs. 43.4%; p< 0.001). Hospitalized RSV+ children in the 2022-23 surge had fewer comorbid conditions (17.1% vs. 21.7%; p< 0.001), required mechanical ventilation less frequently (8.1% vs. 12.4%; p< 0.001), had shorter lengths of hospital stay (median 2 days vs. 3 days; p< 0.001), and lower mortality (0.12% vs. 0.19%; p=0.008) than in pre-pandemic seasons.

Conclusions: RSV+ children in the 2022-23 post-pandemic surge were older, more likely to be previously healthy, required less ICU care and mechanical ventilation, and had shorter hospital stays and lower mortality than in pre-pandemic seasons. The surge of pediatric RSV infections in both vulnerable younger populations and older previously healthy children uncovers epidemiologic shifts essential to understand as new RSV vaccines and prophylactic medications emerge.