The fact that SARS-CoV-2 utilizes ACE2 to enter airway cells along with the fact that ACE2 is a multifunctional enzyme that counter-regulates the ACE-driven mechanisms of the RAS and balances the KKS may therefore explain the serious course of COVID-19, not only in the lungs but systemically [24, 25]. Here, ACE2 is linked to COVID-19.