Two-Year Pathogen Dynamics, Coinfection Features, and Core Risk Factors Associated With Severe Pediatric Acute Respiratory Tract Infections in Hangzhou, China.

BACKGROUND

Acute respiratory tract infections (ARTI) remain a major public health burden in children globally. Nevertheless, regional data regarding postpandemic pathogen shifts, coinfection profiles, and risk factors associated with severe pediatric ARTI in Hangzhou, China, remain scarce.

METHODS

A retrospective observational study was conducted on 6701 hospitalized pediatric patients (0-18 years) with ARTI in Hangzhou, China, from July 2023 to June 2025. Eleven respiratory pathogens were detected using fluorescence PCR-capillary electrophoresis. Univariate and multivariable logistic regression analyses, alongside three machine learning models, were employed to identify risk factors. Age-stratified and coinfection analyses were also performed.

RESULTS

Rhinovirus (RV), Mycoplasma pneumoniae (Mp), and respiratory syncytial virus (RSV) were the most prevalent pathogens. The coinfection network was centered on RV, Mp, and adenovirus, with RV-Mp being the most common dual infection. Mixed infections were associated with severe illness (4.3% vs. 3.5% in single infections vs. 1.6% in pathogen-negative cases). Mp, bocavirus (Boca), and RV infections, along with reduced percentages of lymphocytes, monocytes, and eosinophils, were independent risk factors associated with severe illness, whereas older age was a protective factor. Logistic regression demonstrated the best predictive performance.

CONCLUSIONS

This study elucidates the dynamics of pediatric ARTI pathogens and coinfection characteristics 2 years postpandemic in Hangzhou, China. It identifies key risk factors associated with severe pediatric ARTI, providing essential evidence to inform age-specific clinical prevention, targeted interventions, and public health strategies for pediatric ARTI in the region.