Pediatric Acute Respiratory Virus Hospitalizations: A Population-Based Cohort Study, 2017-2024.

BACKGROUND

Coronavirus disease 2019 (COVID-19) mitigation measures resulted in widespread disruptions to respiratory viruses. The objective of this study was to compare observed and expected pediatric viral acute respiratory infection (ARI)-related hospitalizations, and the characteristics of admitted children, postpandemic.

METHODS

Total and virus-specific ARI-related hospitalization rates were determined using a population-based cohort of youth <18 years in Ontario, Canada between July 2017 and June 2024. Sociodemographic and clinical characteristics were identified from linked administrative data. Expected weekly postpandemic age- and sex-specific admission rates were estimated using Poisson regression; adjusted rate ratios (RRs) and 95% confidence intervals (CIs) were reported.

RESULTS

This cohort included approximately 2.7 million youth per year. There was a sharp reduction in ARIs in 2020/2021, followed by a moderate return in 2021/2022; influenza remained mostly absent (n = 168). An out of season persistence and overwhelming ARI burden occurred in 2022/2023, particularly for RSV (n = 4701 admissions vs 1969-2357 prepandemic) and human metapneumovirus (n = 377 vs 93-127). Overall, more older children (mean age, 38.9-42.8 vs 37.2-37.9 months prepandemic) and fewer males were admitted postpandemic; males were the only group with lower than expected 2022/2023 admissions (RR, 0.63; 95% CI, .57-.70 for all ARIs). COVID-19-related admissions contributed minimally to ARI-related hospitalizations overall, particularly among <5 year olds. Prepandemic seasonality appears to nearly have resumed in 2023/2024.

CONCLUSIONS

Postpandemic disruptions in multiple ARIs substantially influenced the intensity, timing, and characteristics of children seeking health care. Although 2023/2024 was more typical, it is not yet clear when-or if-prepandemic ARI seasonality will resume.

LAY SUMMARY

Substantial, unprecedented changes in several common childhood respiratory viruses occurred in each season following the COVID-19 pandemic, drastically impacting the timing and magnitude of demands placed upon the pediatric health care system, as well as the characteristics of children seeking care.