Figure 3: Complex interaction of ACE-i/ARBs and COVID-19. In COVID-19, the virus downregulates ACE2, which acts as a receptor of SARS-CoV-2. The physiological function of ACE2 is to catalyze angiotensin II to angiotensin 1-7, and acts like a gatekeeper of the RAAS pathway. This leads to angiotensin surge in COVID-19. The ACE-i/ARBs inhibit RAAS pathway and upregulate the ACE2 level. Red arrows represent downregulation and blue arrows represent upregulation. ACE-i, angiotensin-converting enzyme inhibitors; ARBs, angiotensin receptor blockers.