1. Expected survival for less than 48 hours after randomization

2. Child-Pugh stage C hepatic impairment and/or portal hypertension secondary to cirrhosis

3. Stage IV chronic kidney disease or end-stage kidney disease on maintenance hemodialysis

4. Requirement for extra-corporeal membrane oxygenation (ECMO)

5. Acute Myocardial Infarction (AMI)

6. Active bleeding requiring transfusion

7. Concurrent participation in another clinical trial of experimental treatment for SARSCoV-2

8. Female patients who are pregnant or breastfeeding

9. Requirement for concurrent treatment with nitrates

A Trial of GC4419 in Patients With Critical Illness Due to COVID-19