REN and COVID-19: Notably, concern had been raised about the use of renin–angiotensin–aldosterone system (RAAS) blockade and its potential risk on incident AKI in COVID-19 patients based on its potential effect on the reduction of glomerular filtration rate as well as increased susceptibility and severity of COVID-19 by enhancing angiotensin-converting enzyme 2 (ACE2) which is a functional receptor protein for SARS-CoV-27.