OBJECTIVES: Previous studies focusing on pediatric patients hospitalized with severe coronavirus disease 2019 (COVID-19) have been limited to small case series. We aimed to evaluate the characteristics of a large population of pediatric patients with severe COVID-19 and compare them with patients with severe cases of influenza and other respiratory viruses (ORV). METHODS: We performed a cross-sectional study of Brazilian data from the National Epidemiological Surveillance Information System, gathered from January 1st to July 14th, 2020. The sample included 4,784 patients (2,570 with confirmed COVID-19, 659 with influenza, 1,555 with ORV). Outcome measures included clinical features, preexisting comorbidities, pediatric intensive care unit admissions, need for ventilatory support, and death. RESULTS: Compared with the influenza and ORV groups, the COVID-19 group had a higher proportion of newborns and adolescents, as well as lower frequencies of fever, cough, dyspnea, respiratory distress, and desaturation. Although use of invasive ventilatory support was similar among groups, death rate was highest for COVID-19 (15.2% vs. 4.5% vs. 3.2%, p<0.001), with death risk more than three times the other groups (adjusted OR=3.7 [95% CI 2.5-5.6]). The presence of two or more comorbidities further increased this risk (OR=4.8 [95% CI 3.5-6.6]). Preexisting comorbidities were reported in 986 patients with severe COVID-19 (38%). Mortality rate among COVID-19 patients was significantly higher for almost all comorbidities reported. CONCLUSION: Severe COVID-19 had a higher mortality rate than other viral respiratory illnesses, despite the lower frequency of fever, cough, dyspnea, respiratory distress, and desaturation. Death risk was strongly associated with preexisting comorbidities.