CD4 and COVID-19: Regarding the Treg subsets, naïve Treg cells (CD45RA+CD3+CD4+CD25+CD127low+) (Figure S3F) were significantly lower from the day of admission, through day 7, to day 12 in the ICU COVID-19 patients (p < 0.001, p < 0.001, p = 0.022, respectively), while induced Treg cells (CD45RO+CD3+CD4+CD25+CD127low+) (Figure S3G) were lower from admission to day 7 in the ICU COVID-19 patients (p = 0.007 and p < 0.001, respectively).