Counter-regulatory 'Renin-Angiotensin' System-based Candidate Drugs to Treat COVID-19 Diseases in SARS-CoV-2-infected patients. SARS-CoV-2 / COVID-19 and the 'Renin-Angiotensin' System The ubiquitous 'Renin-Angiotensin' system (RAS), also referred to as 'Renin-Angiotensin-Aldosterone' system, plays a crucial physiological role in humans as being a key regulator of renal, cardiovascular and innate immune functions [1, 2]. It appears to