Upamostat, a Serine Protease Inhibitor, or Placebo for Treatment of COVID-19 Disease

Inclusion Criteria: 1. Patients with symptomatic, diagnostically confirmed COVID-19, per RT-PCR or antigen assay of respiratory tract sample. 2. Patient must have either become symptomatic or found positive by RT-PCR or antigen assay within 5 days, whichever is greater, of randomization. 3. Patients must fill out a baseline questionnaire which is reviewed by study personnel to determine eligibility. 4. Males and females ≥age 18 years. 5. Oxygen saturation by pulse oximeter ≥92% on room air 6. Negative urine or serum pregnancy test (if woman of childbearing potential). 7. Females of childbearing potential and males with female partners of childbearing potential must agree to use acceptable contraceptive methods during the study and for at least two months after the last dose of study medication. 8. Ability to complete the daily diary independently. 9. The patient must give informed consent Exclusion Criteria: 1. Patient is in need of acute hospitalization per clinician assessment. 2. Pregnant or nursing women. 3. Unwillingness or inability to comply with procedures required in this protocol. 4. Patient requires supplemental oxygen. 5. Patient is currently receiving, has received within the past 7 days or is expected to receive during the course of the study remdesivir, or other specific antiviral or anticytokine therapy for COVID-19, other than therapeutic monoclonal antibodies allowed or approved in the region in which the patient lives, or systemic corticosteroid equivalent to ≥20 mg daily prednisone/3 mg dexamethasone daily. 6. Patient is currently receiving or has received within 30 days prior to screening any other investigational agent for any indication, including approved agents given for investigational indications (e.g., anti-cytokine treatments). 7. Patient is currently taking or is expected to start taking warfarin, apixaban (Eliquis), or rivaroxaban (Xarelto). Patients may be taking or start on study dabigatran (Pradaxa), standard or low molecular weight heparin.