Seasonal Distribution, Virus-Specific Hematologic Profiles, and Predictors of Hospitalization in Children with Respiratory Viral Infections

Background: Respiratory viral infections are a major cause of morbidity in children worldwide; however, several aspects remain incompletely understood. In particular, hematological changes associated with specific viral pathogens are not well defined, and their potential diagnostic value remains uncertain. In addition, the seasonal distribution of respiratory viruses may vary between years and geographical regions Methods: This retrospective study analyzed pediatric patients presenting to the outpatient clinics at Ankara Bilkent City Hospital between September 2024 and May 2025 who underwent multiplex PCR testing for respiratory viruses. Demographic characteristics, viral etiology, hematological parameters and hospitalization status were analyzed. Results: A total of 1143 patients tested positive for at least one viral pathogen; 91.1% had monoinfection and 8.9% had coinfection. The most commonly detected pathogens were rhinovirus/enterovirus, influenza A and respiratory syncytial virus, with frequencies of 23.7%, 17.7% and 13.7% respectively. Viral positivity peaked during winter, with distinct seasonal distribution patterns across pathogens. Coinfection and comorbid conditions were not significantly associated with hospital admission. In multivariable analysis, younger age and elevated CRP levels were identified as independent predictors of hospitalization. Significant differences in hematological parameters were observed among respiratory viruses, particularly in adenovirus and influenza infections. Conclusions: Respiratory viruses may exhibit distinct seasonal and hematological patterns. Younger age and elevated CRP levels are associated with an increased risk of hospitalization. Routine hematological parameters may provide additional value in clinical evaluation. Further studies are needed to validate these findings.