- participation in any other clinical trial of an experimental treatment for covid-19 (use of hydroxycholoroquine or compassionate use of choloroquine or azithromycin is allowed) - concurrent treatment with other agents with actual or possible direct acting antiviral activity against sars-cov-2 is prohibited < 24 hours prior to study drug/placebo dosing - requiring mechanical ventilation at screening - requiring icu care at admission - nsaid use within 12 hours of randomization or requiring continued nsaid use during this trial - alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 x upper limit of normal (uln) - estimated gfr < 40 ml/min - history of serum creatinine ≥ 2 mg/dl in the previous 28 days - systolic bp < 100 mm hg or diastolic bp < 65 mm hg - hypersensitivity to acei - history of angioedema - outpatient use of ace inhibitor or angiotensin ii receptor blocker in the last 7 days - history of renal artery stenosis - serum potassium ≥ 5.1 meq/l - pregnancy or breastfeeding - use of aliskiren, amifostine, lithium, sacubitril within 7 days

- participation in any other clinical trial of an experimental treatment for covid-19 (use of hydroxycholoroquine or compassionate use of choloroquine or azithromycin is allowed) - concurrent treatment with other agents with actual or possible direct acting antiviral activity against sars-cov-2 is prohibited < 24 hours prior to study drug/placebo dosing - requiring mechanical ventilation at screening - requiring icu care at admission - nsaid use within 12 hours of randomization or requiring continued nsaid use during this trial - alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 x upper limit of normal (uln) - estimated gfr < 40 ml/min - history of serum creatinine ≥ 2 mg/dl in the previous 28 days - systolic bp < 100 mm hg or diastolic bp < 65 mm hg - hypersensitivity to acei - history of angioedema - outpatient use of ace inhibitor or angiotensin ii receptor blocker in the last 7 days - history of renal artery stenosis - serum potassium ≥ 5.1 meq/l - pregnancy or breastfeeding - use of aliskiren, amifostine, lithium, sacubitril within 7 days