ACE2 and COVID-19: It is shown that ACE2 over-expression has led to the severity of SARS-CoV disease in mice.41 Studies also indicated that high activities of mACE2 and/or ADAM-17 may be involved in the severity of COVID-19.38,41 Contrary to the globally observed data, female rats with higher expression of ACE2 are reported to have poorer prognosis.7 Stelzig, et al6 reported that normal human bronchial epithelial (NHBE) cells that were treated with 17β-estradiol (E2) had a lower expression level of ACE2 messenger ribonucleic acid (mRNA) compared with NHBE cells that were treated with the vehicle, ethanol.