Medical complexity was defined by the Pediatric Medical Complexity Algorithm. The sample was defined as children aged 18 years or younger with a COVID-19 diagnosis during an emergency department or inpatient encounter in hospitals that reported both emergency department and inpatient encounters to Premier Healthcare Database Special COVID-19 Release, March 2020 through January 2021. Each panel represents results of a single generalized linear model with Poisson distribution and log link function, that includes the following covariates: medical complexity (presence of noncomplex chronic disease, presence of complex chronic disease, and no chronic disease as reference group), age group, sex, race/ethnicity, payer type, hospital urbanicity, hospital US Census region, admission month, and admission month squared.