Assessing the Effect of Viral Coinfection on Pneumonia Diagnosis Odds in Children and Adolescents with Influenza

Introduction. Influenza infections pose a major public health concern, especially in children and adolescents at high risk for severe pneumonia. Coinfections with multiple pathogens exacerbate respiratory infections. This study assessed the effect of coinfections on pneumonia diagnosis in this population. Methods. A cross-sectional analysis was conducted using data from a nationwide epidemiological surveillance system in Mexico. Data from 2,057 RT-PCR-confirmed influenza cases in patients aged 15 years and younger, recorded between January and October 26, 2024, were analyzed. The primary outcome was pneumonia diagnosis, with associations to coinfection and other risk factors assessed using odds ratios (OR) and 95% confidence intervals (CI). Results. Pneumonia was diagnosed in 36.0% of the cases, with coinfection more common among those diagnosed with pneumonia (7.4% vs. 3.1%, < 0.001). In the multiple regression model, coinfection was associated with a 95% increase in pneumonia odds (OR = 1.95, 95% CI 1.27 – 3.00). Younger age, obesity, and immunosuppression were also associated with higher odds of pneumonia. Conclusions. Our findings suggest that viral coinfections increase the odds of pneumonia in pediatric influenza cases. Widespread influenza vaccination remains critical for reducing influenza-related disease burden, while systematic coinfection screening would enable timely clinical interventions.