inclusion criteria: 1. participant is hospitalized with severe covid-19 illness, defined in accordance with the food and drug administration (fda) guidance for industry - covid-19: developing drugs and biological products for treatment or prevention (may 2020): a. severe illness: i. symptoms suggestive of severe systemic illness with covid-19, which could include any symptom of moderate illness or shortness of breath at rest, or respiratory distress ii. clinical signs indicative of severe systemic illness with covid-19, such as respiratory rate ≥30 per minute, heart rate ≥125 per minute, spo₂ ≤93% on room air at sea level or partial pressure of oxygen pao₂/fraction of inspired oxygen fio₂ \<300. 2. participant has a positive virologic nucleic acid amplification test (naat) indicating sars-cov-2 infection in a sample collected \<72 hours prior to randomization. 3. participant is between the ages of 18 and 80 years at the time of enrollment. 4. participant provides informed consent prior to initiation of any study procedures. 5. participant agrees to not participate in another clinical trial for the treatment of covid 19 or sars-cov-2 through day 28. 6. participant has adequate hematologic status (in the absence of transfusion and growth factor support for at least 28 days), defined as follows: 1. absolute neutrophil count (anc) ≥1.5 × 10⁹/l 2. platelet count ≥75 × 10⁹/l 3. hemoglobin ≥9 g/dl. 7. participant has an eastern cooperative oncology group (ecog) performance score of 0-2.

inclusion criteria: 1. participant is hospitalized with severe covid-19 illness, defined in accordance with the food and drug administration (fda) guidance for industry - covid-19: developing drugs and biological products for treatment or prevention (may 2020): a. severe illness: i. symptoms suggestive of severe systemic illness with covid-19, which could include any symptom of moderate illness or shortness of breath at rest, or respiratory distress ii. clinical signs indicative of severe systemic illness with covid-19, such as respiratory rate ≥30 per minute, heart rate ≥125 per minute, spo₂ ≤93% on room air at sea level or partial pressure of oxygen pao₂/fraction of inspired oxygen fio₂ \<300. 2. participant has a positive virologic nucleic acid amplification test (naat) indicating sars-cov-2 infection in a sample collected \<72 hours prior to randomization. 3. participant is between the ages of 18 and 80 years at the time of enrollment. 4. participant provides informed consent prior to initiation of any study procedures. 5. participant agrees to not participate in another clinical trial for the treatment of covid 19 or sars-cov-2 through day 28. 6. participant has adequate hematologic status (in the absence of transfusion and growth factor support for at least 28 days), defined as follows: 1. absolute neutrophil count (anc) ≥1.5 × 10⁹/l 2. platelet count ≥75 × 10⁹/l 3. hemoglobin ≥9 g/dl. 7. participant has an eastern cooperative oncology group (ecog) performance score of 0-2.

inclusion criteria: participant is hospitalized with severe covid-19 illness, defined in accordance with the food and drug administration (fda) guidance for industry - covid-19: developing drugs and biological products for treatment or prevention (may 2020): a. severe illness: i. symptoms suggestive of severe systemic illness with covid-19, which could include any symptom of moderate illness or shortness of breath at rest, or respiratory distress ii. clinical signs indicative of severe systemic illness with covid-19, such as respiratory rate ≥30 per minute, heart rate ≥125 per minute, spo₂ ≤93% on room air at sea level or partial pressure of oxygen pao₂/fraction of inspired oxygen fio₂ <300. participant has a positive virologic nucleic acid amplification test (naat) indicating sars-cov-2 infection in a sample collected <72 hours prior to randomization. participant is between the ages of 18 and 80 years at the time of enrollment. participant provides informed consent prior to initiation of any study procedures. participant agrees to not participate in another clinical trial for the treatment of covid 19 or sars-cov-2 through day 28. participant has adequate hematologic status (in the absence of transfusion and growth factor support for at least 28 days), defined as follows: absolute neutrophil count (anc) ≥1.5 × 10⁹/l platelet count ≥75 × 10⁹/l hemoglobin ≥9 g/dl. participant has an eastern cooperative oncology group (ecog) performance score of 0-2.

inclusion criteria: participant is hospitalized with severe covid-19 illness, defined in accordance with the food and drug administration (fda) guidance for industry - covid-19: developing drugs and biological products for treatment or prevention (may 2020): a. severe illness: i. symptoms suggestive of severe systemic illness with covid-19, which could include any symptom of moderate illness or shortness of breath at rest, or respiratory distress ii. clinical signs indicative of severe systemic illness with covid-19, such as respiratory rate ≥30 per minute, heart rate ≥125 per minute, spo₂ ≤93% on room air at sea level or partial pressure of oxygen pao₂/fraction of inspired oxygen fio₂ <300. participant has a positive virologic nucleic acid amplification test (naat) indicating sars-cov-2 infection in a sample collected <72 hours prior to randomization. participant is between the ages of 18 and 80 years at the time of enrollment. participant provides informed consent prior to initiation of any study procedures. participant agrees to not participate in another clinical trial for the treatment of covid 19 or sars-cov-2 through day 28. participant has adequate hematologic status (in the absence of transfusion and growth factor support for at least 28 days), defined as follows: absolute neutrophil count (anc) ≥1.5 × 10⁹/l platelet count ≥75 × 10⁹/l hemoglobin ≥9 g/dl. participant has an eastern cooperative oncology group (ecog) performance score of 0-2.

inclusion criteria: 1. participant is hospitalized with severe covid-19 illness, defined in accordance with the food and drug administration (fda) guidance for industry - covid-19: developing drugs and biological products for treatment or prevention (may 2020): a. severe illness: i. symptoms suggestive of severe systemic illness with covid-19, which could include any symptom of moderate illness or shortness of breath at rest, or respiratory distress ii. clinical signs indicative of severe systemic illness with covid-19, such as respiratory rate ≥30 per minute, heart rate ≥125 per minute, spo₂ ≤93% on room air at sea level or partial pressure of oxygen pao₂/fraction of inspired oxygen fio₂ <300. 2. participant has a positive virologic nucleic acid amplification test (naat) indicating sars-cov-2 infection in a sample collected <72 hours prior to randomization. 3. participant is between the ages of 18 and 80 years at the time of enrollment. 4. participant provides informed consent prior to initiation of any study procedures. 5. participant agrees to not participate in another clinical trial for the treatment of covid 19 or sars-cov-2 through day 28. 6. participant has adequate hematologic status (in the absence of transfusion and growth factor support for at least 28 days), defined as follows: 1. absolute neutrophil count (anc) ≥1.5 × 10⁹/l 2. platelet count ≥75 × 10⁹/l 3. hemoglobin ≥9 g/dl. 7. participant has an eastern cooperative oncology group (ecog) performance score of 0-2.

inclusion criteria: 1. participant is hospitalized with severe covid-19 illness, defined in accordance with the food and drug administration (fda) guidance for industry - covid-19: developing drugs and biological products for treatment or prevention (may 2020): a. severe illness: i. symptoms suggestive of severe systemic illness with covid-19, which could include any symptom of moderate illness or shortness of breath at rest, or respiratory distress ii. clinical signs indicative of severe systemic illness with covid-19, such as respiratory rate ≥30 per minute, heart rate ≥125 per minute, spo₂ ≤93% on room air at sea level or partial pressure of oxygen pao₂/fraction of inspired oxygen fio₂ <300. 2. participant has a positive virologic nucleic acid amplification test (naat) indicating sars-cov-2 infection in a sample collected <72 hours prior to randomization. 3. participant is between the ages of 18 and 80 years at the time of enrollment. 4. participant provides informed consent prior to initiation of any study procedures. 5. participant agrees to not participate in another clinical trial for the treatment of covid 19 or sars-cov-2 through day 28. 6. participant has adequate hematologic status (in the absence of transfusion and growth factor support for at least 28 days), defined as follows: 1. absolute neutrophil count (anc) ≥1.5 × 10⁹/l 2. platelet count ≥75 × 10⁹/l 3. hemoglobin ≥9 g/dl. 7. participant has an eastern cooperative oncology group (ecog) performance score of 0-2.