Evolving Characteristics of Children and Youth With COVID-19 or MIS-C in US Children’s Hospitals

OBJECTIVE To describe trends in sociodemographic and clinical characteristics in children and youth treated at US children’s hospitals for COVID-19 or multisystem inflammatory syndrome in children (MIS-C). METHODS We conducted a serial cross-sectional study using data from the Pediatric Health Information System (March 2020 to June 2024). Patients were aged 21 years or younger and hospitalized with COVID-19 or MIS-C or discharged from emergency departments with COVID-19 diagnosis (comparator). Sociodemographic and clinical characteristics of subjects were tracked by pandemic wave. Community-level resources were assessed using the Child Opportunity Index. Temporal changes were assessed descriptively and with logistic regression models incorporating interaction terms between covariates and pandemic waves. RESULTS Among 295 264 children and youth, 94.5% were identified with nonhospitalized COVID-19, 3.4% with hospitalized COVID-19, and 2.1% with MIS-C. Compared with early waves of the pandemic, hospitalizations for COVID-19 and MIS-C increased disproportionately among children younger than 12 years and non-Hispanic white populations by the Omicron era. Although community-level differences in hospitalizations for COVID-19 and MIS-C were observed early in the pandemic, these differences diminished over time. Trends in hospitalized SARS-CoV-2–associated disease varied by comorbid conditions, with early excesses in hospitalizations followed by declines among those diagnosed with obesity, hematologic disorders, and immunodeficiencies. CONCLUSIONS The pediatric populations at greatest risk for hospitalization from COVID-19 or MIS-C in the United States changed over time, with increasing risks among younger and non-Hispanic white patients, reduced differences in hospitalizations based on community-level characteristics, and decreasing risks in those with obesity and several other comorbidities. These findings may inform efforts for targeted prevention (eg, vaccination).