BackgroundPatient characteristics, clinical care, resource use, and outcomes associated with hospitalization for coronavirus disease (COVID-19) in Canada are not well described.MethodsWe described all adult discharges from inpatient medical services and medical-surgical intensive care units (ICU) between November 1, 2019 and June 30, 2020 at 7 hospitals in Toronto and Mississauga, Ontario. We compared patients hospitalized with COVID-19, influenza and all other conditions using multivariable regression models controlling for patient age, sex, comorbidity, and residence in long-term-care.ResultsThere were 43,462 discharges in the study period, including 1,027 (3.0%) with COVID-19 and 783 (2.3%) with influenza. Patients with COVID-19 had similar age to patients with influenza and other conditions (median age 65 years vs. 68 years and 68 years, respectively, SD<0.1). Patients with COVID-19 were more likely to be male (59.1%) and 11.7% were long-term care residents. Patients younger than 50 years accounted for 21.2% of all admissions for COVID-19 and 24.0% of ICU admissions. Compared to influenza, patients with COVID-19 had significantly greater mortality (unadjusted 19.9% vs 6.1%, aRR: 3.47, 95%CI: 2.57, 4.67), ICU use (unadjusted 26.4% vs 18.0%, aRR 1.52, 95%CI: 1.27, 1.83) and hospital length-of-stay (unadjusted median 8.7 days vs 4.8 days, aRR: 1.40, 95%CI: 1.20, 1.64), and not significantly different 30-day readmission (unadjusted 8.6% vs 8.2%, aRR: 1.01, 95%CI: 0.72, 1.42).InterpretationAdults hospitalized with COVID-19 during the first wave of the pandemic used substantial hospital resources and suffered high mortality. COVID-19 was associated with significantly greater mortality, ICU use, and hospital length-of-stay than influenza.