AimEarly diagnosis and treatment are crucial for the survival of severe Coronavirus Disease 2019 (COVID-19) patients, but data with regard to risk factors for disease progression from milder COVID-19 to severe COVID-19 remain scarce.MethodsWe conducted a retrospective analysis on 116 patients.ResultsThree factors were observed to be independently associated with progression to severe COVID-19 during 14 days after admission: (a) age 65 years or older (hazard ratio [HR] = 8.456; 95% CI: 2.706–26.426); (b) creatine kinase (CK) ≥ 180 U/L (HR = 3.667; 95% CI: 1.253–10.733); and (c) CD4+ T-cell counts ConclusionsAge ≥ 65 years, CK ≥ 180 U/L, and CD4+ T-cell counts