Indeed, a potential upregulation of aromatase enzyme in adipose tissue during critical illness, possibly due to inflammatory cytokines,35,41 is likely to stimulate a multifold increase in conversion of testosterone to estradiol.35,36 Consistent with this, we found that higher estradiol to testosterone ratio was associated with inflammatory cytokine concentration, COVID-19 severity, ventilator use, ICU admission, and mortality. This evidence concerns the gene CYP19A1 and COVID-19.