To investigate how age, sex, and comorbidities affect the survival of hospitalized coronavirus disease 2019 (COVID-19) patients. We retrospectively analyzed the records of 4014 consecutive adults hospitalized for COVID-19 in a tertiary-level institution from March 2020 to March 2021. The median age was 74 years. A total of 2256 (56.2%) patients were men. The median Charlson-comorbidity-index (CCI) was 4 points; 3359 (82.7%) patients had severe or critical COVID-19. A significant interaction between age, sex, and survival (P<0.05) persisted after adjustment for CCI. In patients <57 years, male sex was related to a favorable (odds ration OR 0.50, 95% confidence interval CI 0.29-0.86), whereas in patients ≥57 years it was related to an unfavorable prognosis (OR 1.19, 95% CI 1.04-1.37). Comorbidities associated with inferior survival independently of age, sex, and severe/critical COVID-19 on admission were chronic heart failure, atrial fibrillation, acute myocardial infarction, acute cerebrovascular insult, history of venous thromboembolism, chronic kidney disease, major bleeding, liver cirrhosis, mental retardation, dementia, active malignant disease, metastatic malignant disease, autoimmune/rheumatic disease, bilateral pneumonia, and other infections on admission. Among younger patients, female sex might lead to an adverse prognosis due to undisclosed reasons (differences in fat tissue distribution, hormonal status, and other mechanisms). Patient subgroups with specific comorbidities require additional considerations during hospital stay for COVID-19. Future studies focusing on sex differences and potential interactions are warranted.