TMPRSS2 and major depressive disorder: In our previous study, 42 of 96 had stated on their own account that they had mild depression 14; Ageusia and anosmia during COVID-19 disease period were believed to be related to ACE2 and TMPRSS2 expression on epithelial cells 15, but in this study, we found those symptoms occurred during the recovery period, probably related to mental conditions 16.