Characteristics and Outcomes of Children Hospitalized With COVID-19 During Early Pandemic and Delta Variant.

Background: Children were less affected by severe illness as compared to adults at the start of the COVID-19 pandemic. As the pandemic progressed and variants emerged, pediatric hospitalizations increased, and some previously healthy children developed multisystem inflammatory disorder. The aim of this study was to describe the characteristics and outcomes of children hospitalized with COVID-19 from the beginning of the pandemic through the Delta variant. Methods: Data were collected retrospectively for children hospitalized during March 2020-November 2021 with a diagnosis of COVID-19. Admissions were classified as early pandemic or during the Delta variant, and outcomes were compared between the time periods. Primary outcome measures were hospital length of stay and use of respiratory support. The number of admissions/month was the secondary outcome. Results: There were 784 hospital admissions: 400 during early pandemic and 378 during the Delta period. Forty-four percent had an underlying medical condition, and 78% were not eligible for COVID-19 vaccination. Oxygen was the most common respiratory support modality and was required more often during Delta (P < .001). Hospital stay was longer during the Delta period (P < .001), and the number of monthly admissions was higher. A statistically significant but low correlation was identified between body mass index (BMI) Z score and stay (P < .001, r = 0.19). Conclusions: The Delta variant was associated with increased hospital length of stay and use of respiratory support compared to the early pandemic period. Children with preexisting medical conditions were more likely to require respiratory support and have longer hospitalization than others. Higher BMI Z score was also weakly associated with longer length of stay. The reason for admission was attributed to causes other than COVID-19 for the majority of admissions except during the Delta period.