It is noteworthy that the efficacy of mAbs against COVID-19 consists in linking directly to the receptor-binding domain of spike protein (through which the virus may be able to recognize and bind the angiotensin-converting enzyme-2 (ACE2) receptor and enabling the virus to enter human cells), reducing both the mortality and the morbidity risk, as well as the length of hospitalization [29,30]. Here, ACE2 is linked to COVID-19.