Common respiratory virus spectrum and epidemiological trends among children in Northwest China during the post-COVID-19 era

Objective To explore the epidemiology of common pediatric respiratory viruses among children in the post–COVID-19 era. Methods Retrospective analysis of children with respiratory symptoms who visited our hospital between March 2023 and May 2025 was conducted. Influenza A/B (Flu A/B) antigen testing was performed for 151,809 children; nucleic acid testing for respiratory syncytial virus ༈RSV༉, adenovirus ༈ADV༉, human metapneumovirus (HMPV), and parainfluenza viruses (PIV) I–III was performed for 35,326 children. Demographic and laboratory data were analyzed. Results Across two post-pandemic seasons, most viruses resurged; HMPV and PIV II peaked more prominently in season 2. RSV showed the highest positivity, whereas Flu A had the most positive cases. RSV and PIV III predominated in infants; Flu A, HMPV, and PIV I/II predominated in preschoolers; and Flu B and ADV predominated in school-aged children. Flu A, Flu B, and the RSV shared a winter peak and summer trough, whereas the PIV subtypes displayed distinct seasonality. Clinically, Flu A/B was associated mainly with acute upper respiratory infections; non-severe pneumonia was associated predominantly with RSV, ADV, HMPV, and PIVs. Coinfections were most frequent with ADV and HMPV and least frequent with Flu A and Flu B; the most common dual and triple coinfections were “RSV + ADV” and “RSV + ADV + Flu B”. Conclusion In the post-COVID-19 era, the age distribution, seasonality, and coinfection patterns of pediatric respiratory viruses shifted. Viruses with high detection and coinfection propensities warrant strengthened surveillance and tailored control strategies.