Pediatric Respiratory Hospitalizations in the Pre-COVID-19 Era: The Contribution of Viral Pathogens and Comorbidities to Clinical Outcomes, Valencia, Spain.

Viral respiratory diseases place a heavy burden on the healthcare system, with children making up a significant portion of related hospitalizations. While comorbidities increase the risk of complications and poor outcomes, many hospitalized children lack clear risk factors. As new vaccines for respiratory viral diseases emerge, this study examined pediatric respiratory hospitalizations, focusing on viral etiology, complication rates, and the impact of comorbidities to guide future policy. Data were analyzed from eight pre-COVID influenza seasons (2011/2012-2018/2019) involving patients under 18 years hospitalized with respiratory complaints across 4-10 hospitals in Valencia, Spain. Respiratory specimens were tested for eight viral targets using multiplex real-time reverse-transcription polymerase chain reaction. Demographics, clinical outcomes, discharge diagnoses, and laboratory results were examined. Among the hospitalized children, 26% had at least one comorbidity. These children had higher rates of pneumonia, asthma exacerbation, and pneumothorax, and were twice as likely to require ICU admission, though mechanical ventilation and length of stay were similar to those without comorbidities. Respiratory syncytial virus (RSV) was the most common virus detected (23.1%), followed by rhinovirus/enterovirus (9.5%) and influenza (7.2%). Viral codetection decreased with age, occurring in 4.6% of cases. Comorbidities increase the risk of complications in pediatric respiratory illnesses, however, healthcare utilization is driven largely by otherwise healthy children. Pediatric viral vaccines could reduce this burden and should be further evaluated.