ObjectiveTo analyze the epidemiological and clinical characteristics of severe cases of coronavirus disease 2019 (COVID-19) in order to provide reference for clinical diagnosis and treatment.MethodThe epidemiological histories, clinical characteristics, laboratory examinations, chest images, and treatment outcomes of 20 confirmed cases of severe COVID-19 admitted to Public Health Clinical Center of Chengdu from January 16th to February 5th, 2020 were retrospectively analyzed.ResultsAmong the 20 patients with severe COVID-19, 12 were male and 8 were female. The age ranged from 34 to 84 years old, with an average of (57.4±16.5) years old. Thirteen patients (65.0%) had one or more co-existing diseases, such as hypertension (9 cases), diabetes (6 cases), and coronary atherosclerotic heart disease (4 cases). Eleven cases (55.0%) had a history of living or traveling in Wuhan, 4 cases (20.0%) had a history of living in non-Wuhan areas of Hubei Province, 3 cases (15.0%) had a history of contact with confirmed COVID-19 patients, while 2 cases had no above-mentioned epidemiological history, but had a history of traveling in non-epidemic areas. The main symptoms were fever (100.0%), cough (100.0%), shortness of breath (75.0%), and fatigue (65.0). Some patients developed into acute respiratory distress syndrome in 3-10 d after onset. The white blood cell count of the patients was normal or decreased, the hypersensitive C-reactive protein and serum amyloid protein significantly increased, while the CD4+ T lymphocyte count and CD56+ natural killer cell count significantly decreased. Sixteen patients (80.0%) were given transnasal hyperbaric oxygenation [among whom 6 patients (30.0%) were transferred to non-invasive ventilator after no improvement], 3 patients (15.0%) were given tracheal intubated ventilator, and 1 patient (5.0%) was treated by tracheal intubated ventilator combined with extracorporeal membrane oxygenation to support breathing. By April 8th, 2020, 3 patients died and the remaining 17 had been cured and discharged, with an average length of hospital stay of 21.4 d. The 3 death cases were all elderly with underlying diseases such as heart disease and pulmonary disease.ConclusionsSevere COVID-19 is associated with hypertension, diabetes, heart disease, and other basic diseases, and some patients develope acute respiratory distress syndrome. Respiratory support may help to improve prognosis.