Patient selection
This study was approved by the institutional ethics board of the Henan Provincial People’s Hospital (ethics approval No: 2020[71]). The Henan Provincial People’s Hospital was assigned responsibility for the treatments of patients with severe COVID-19. We conducted an exploratory study of all the 52 patients with COVID-19 admitted to the hospital from January 10 to March 30, 2020. The diagnosis of COVID-19 was based on the China National Health Commission (NHC) Guidelines for the Diagnosis and Treatment of COVID-19. Confirmed cases had radiologic evidence of pneumonia or infiltrate on chest CT. The methodology of RT-PCR used has been previously reported (Wang et al., 2020).