Clinical Presentation, Laboratory Findings, Complications, and Mortality of Influenza during the Epidemic of October 2019-February 2020 in Iran

Background: Influenza remains a major cause of pediatric morbidity worldwide. We evaluated clinical characteristics, complications, and outcomes of influenza infection in children during Iran's 2019-2020 epidemic. Methods: This cross-sectional study analyzed 357 hospitalized children (<15 yr) with PCR-confirmed influenza at a tertiary center in Qom, Iran (Oct 2019-Feb 2020), representing 375 total PCR-positive cases after excluding 18 with incomplete data. Results: Among 357 patients (mean age 3.2±2.1 yr; 61.3% male), fever (89.6%) and cough (76.8%) were most common. Laboratory findings included lymphopenia (26.3%) and leukopenia (21.8%). Complications occurred in 70 patients (19.6%), including pneumonia (4.8%), otitis media (4.5%), myositis (4.5%), sinusitis (2.8%), and seizures (2.8%). No mortality was observed. Conclusions: Nearly 20% of hospitalized children with influenza developed complications, primarily respiratory and musculoskeletal. While no deaths occurred, the substantial complication rate underscores the importance of early detection and management in high-risk pediatric populations.