PEDIATRIC influenza hospitalizations shifted after the COVID-19 pandemic, with altered seasonality, virus type, and shorter stays.
Pediatric Influenza Patterns Across 2017–2025
Researchers reviewed records for 553 children aged 0–18 years who were hospitalized with laboratory-confirmed influenza at a pediatric infectious disease center in Bydgoszcz, Poland, from September 2017 to August 2025. The team compared epidemiology and clinical characteristics across three periods: pre-pandemic, pandemic, and post-pandemic. Analyses assessed seasonal timing, influenza type, demographics, and length of stay.
COVID-19 Pandemic Reshaped Pediatric Influenza Seasonality
Hospitalizations varied markedly by season, reaching a low in 2021/22 (18 admissions) and a high in 2024/25 (175 admissions). In the pre-pandemic and post-pandemic periods, peak activity clustered in January to March. During the pandemic, admissions showed a bimodal pattern, with increases in December and again in March to April, suggesting a redistribution of seasonal timing rather than a simple delay.
Influenza A predominated throughout, but its share fell during the pandemic compared with pre-pandemic and post-pandemic years (56.7% versus 89.2% and 73.2%, respectively). Median length of hospital stay shortened from 5 days pre-pandemic to 4 days during and after the pandemic, indicating a modest shift in inpatient course across the study periods.
Implications for Clinicians and Public Health
Notably, none of the hospitalized children were vaccinated, highlighting an actionable prevention gap and underscoring the importance of influenza vaccination in routine pediatric care. The authors emphasized that ongoing surveillance is needed to detect future shifts in pediatric influenza timing and subtype distribution, particularly as respiratory viral infections continue to recalibrate after major population-level disruptions.
For clinicians, the findings support staying alert to atypical peaks when evaluating febrile respiratory illness, as timing may not fully mirror pre-2020 norms. They also suggest that local epidemiology can inform diagnostic testing thresholds and inpatient planning during high-incidence seasons. From a health systems perspective, the post-pandemic rebound, with the highest admission volume observed in 2024/25, highlights how rapid changes in circulation can translate into pediatric bed demand.
As a single-center retrospective study, results may not generalize to all settings, and the analysis does not establish causality. Even so, the consistent shifts observed across multiple seasons reinforce the need for sustained monitoring and targeted vaccination strategies to mitigate pediatric influenza burden in the post-pandemic period.
Reference: Wasielewska Z et al. The Impact of the COVID-19 Pandemic on the Epidemiology of Influenza in Hospitalised Children in the Years 2017-2025. Viruses. 2025;18(1):52.
