1. In the abstract, we missed a piece of information. The correct sentence should be "In this retrospective study, we included 550 critically ill COVID-19 patients who need mechanical ventilation (63.5%) and oxygen therapy (35.6%) in Tongji Hospital, Wuhan, from February 1, 2020 to April 4, 2020." 2. We mistakenly put an approval number from Tongji Hospital ethics committee in the paper (IRBID: TJ-C20200113). The correct number should be TJ-IRB20200229. 3. We mistakenly filled some data in Table 1 and the correct Table 1 (the corrected data are in boldface) should be as follows.