ACE2 and COVID-19: In conclusion, the high affinity of SARS-CoV-2 to ACE2 in addition to the wide distribution of ACE2 and TMPRSS2 or other proteases involved in S priming, such as furin and cathepsin L, may define the high SARS-CoV-2 tropism and systemic clinical manifestation of COVID-19, varying from subclinical symptoms to multiple organ damage [3,16,34,35].