Epidemiology, Bacterial Coinfection Risk Factors, and Inflammatory Markers in Children with RSV, AdV, and hMPV Pneumonia in Zunyi, China

Background Community acquired pneumonia (CAP) is a major cause of illness and death in children under five worldwide. This study characterized the epidemiology of RSV/AdV/hMPV associated CAP in Zunyi children and identified bacterial co-infection risk factors, to provide a scientific basis for individualized pediatric CAP management in this region. Methods A retrospective analysis of clinical data from 2315 children with CAP admitted to Zunyi First People's Hospital (Third Affiliated Hospital of Zunyi Medical University) between January and December 2025 was performed. Univariate and multivariate logistic regression analyses identified risk factors for bacterial co-infection, and receiver operating characteristic (ROC) curve analysis evaluated the predictive value of inflammatory markers. Results A total of 2,315 children with CAP were enrolled. The RSV positivity rate (22.76%) was significantly higher than that for AdV (9.72%) and hMPV (9.84%, p <0.05). Single virus pneumonia (SVP) and viral and bacterial co-infected pneumonia (VBCP) were the main types for all three viruses. RSV infection peaked in autumn and winter, with the highest positivity in children under 1 year. AdV infection occurred year-round and was most common in children aged 1–5 years. hMPV infection was concentrated from January to April, predominantly in children aged 1–3 years. Children with RSV pneumonia were the youngest and had obvious wheezing. Children with AdV pneumonia had the highest rates of high fever, tonsillar enlargement, and sepsis, the shortest hospital stay, and significantly higher IL-6 and WBC levels. Multivariate logistic regression showed that elevated IL-6 was an independent risk factor for RSV-associated VBCP (OR=1.031, 95% CI: 1.011–1.052, P =0.002), AdV-associated VBCP (OR=1.035, 95% CI: 1.015–1.056, P =0.001), and hMPV-associated VBCP (OR=1.026, 95% CI: 1.006–1.046, P =0.009). For RSV-associated VBCP, WBC was an additional independent risk factor (OR=1.062, 95% CI: 1.005–1.122, P =0.032). No other indicators exhibited independent predictive value. ROC curve analysis demonstrated that combined inflammatory marker detection had predictive value for VBCP. Conclusions RSV, AdV, and hMPV cause different patterns of illness and inflammation in children with pneumonia in Zunyi. When these viruses co-occur with bacteria, the disease becomes more severe, and the risks vary by virus. High IL-6 levels are a shared, early warning sign of viral and bacterial co-infection for all three viruses.