Considering that (a) we have detected the presence of ACE2 in saliva through the methodology used in this study (data no shown) and (b) the presence of the virus in saliva is known in subjects who are positive for COVID-19 [15], we believe that the changes demostrated in the ACE2 activity preinhibited by HCQ induced by the spike glycoprotein of SARS-CoV-2 could be conveniently used as a diagnostic tool to evaluate the presence of the said virus in saliva. Here, ACE2 is linked to COVID-19.