Subjects (in Part 1 and Part 2) who meet any of the following criteria must be excluded from the study: 1. Participation in any other clinical trial of an experimental treatment for COVID-19 or participation in another interventional clinical trial, including an expanded access trial. 2. Concurrent treatment with other agents with actual or possible direct acting antiviral activity against SARS CoV 2 infection <24 hours prior to study drug dosing except for remdesivir. 3. Uncontrolled hypertension (systolic blood pressure >150 mmHg and/or diastolic blood pressure >100 mmHg), unstable angina, congestive heart failure of any New York Respiratory Association classification, serious cardiac arrhythmia requiring treatment (exceptions: atrial fibrillation, paroxysmal supraventricular tachycardia), or history of myocardial infarction within 12 months of enrollment. 4. Hypotension requiring vasoactive peptides, such as dopamine, norepinephrine, epinephrine, or dobutamine. 5. Renal function impairment (creatinine clearance [Cr. Cl.] <50 mL/min, based on Modification of Diet in Renal Disease calculation). 6. Liver function impairment a. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) >5 × upper limit of normal (ULN), or ALT/AST >3 × ULN plus total bilirubin >2 × ULN. b. Total bilirubin >1.5 × ULN, unless the subject has known Gilbert’s syndrome. 7. Platelet count <50 000/µL 8. Multi-organ failure.

Subjects (in Part 1 and Part 2) who meet any of the following criteria must be excluded from the study: 1. Participation in any other clinical trial of an experimental treatment for COVID-19 or participation in another interventional clinical trial, including an expanded access trial. 2. Concurrent treatment with other agents with actual or possible direct acting antiviral activity against SARS CoV 2 infection <24 hours prior to study drug dosing except for remdesivir. 3. Uncontrolled hypertension (systolic blood pressure >150 mmHg and/or diastolic blood pressure >100 mmHg), unstable angina, congestive heart failure of any New York Respiratory Association classification, serious cardiac arrhythmia requiring treatment (exceptions: atrial fibrillation, paroxysmal supraventricular tachycardia), or history of myocardial infarction within 12 months of enrollment. 4. Hypotension requiring vasoactive peptides, such as dopamine, norepinephrine, epinephrine, or dobutamine. 5. Renal function impairment (creatinine clearance [Cr. Cl.] <50 mL/min, based on Modification of Diet in Renal Disease calculation). 6. Liver function impairment a. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) >5 × upper limit of normal (ULN), or ALT/AST >3 × ULN plus total bilirubin >2 × ULN. b. Total bilirubin >1.5 × ULN, unless the subject has known Gilbert’s syndrome. 7. Platelet count <50 000/µL 8. Multi-organ failure.