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

Abstract

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.

Keywords: children; comorbidities; complications; hospitalizations; respiratory viruses; severity; viral codetection.

Figure 1

Patient selection process.

Figure 2

Complications by presence of comorbidity. ^a Odd ratio for complication when presenting at least one underlying conditions at admission (otherwise healthy as reference). Abbreviation: CI, confidence interval.

Figure 3

Distribution of respiratory viral pathogens detected by RT-PCR by age group. ^a Bocavirus represents 0.5% of the detected viruses in this age group. Influenza includes influenza A(H1N1)pdm09, influenza A(H3N2), influenza B/Yamagata-lineage, influenza B/Victoria-lineage, and influenza not subtyped or with no lineage.

Figure 4

Distribution of selected complications by respiratory viral pathogens detected by RT-PCR, Valencia, Spain 2011/12 through 2018/19. Complications were not mutually exclusive, and the same patient may have developed more than one complication. Influenza includes influenza A(H1N1)pdm09, influenza A(H3N2), influenza B/Yamagata-lineage, influenza B/Victoria-lineage, and influenza not subtyped or with no lineage.