ACE2 and COVID-19: Although this was not the subject of this analysis, when discussing the risk factors for the severe course of COVID-19, it is impossible not to mention the role of host genetic diversity that may modify its immune response [36], or host genetic differences regarding the angiotensin-converting enzyme-2 (ACE-2) to which the spike protein of SARS-CoV-2 binds to enter the host cells [37].