key inclusion criteria: has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization and no alternative explanation for current clinical condition. a historical record of positive result from test conducted ≤72 hours prior to randomization is acceptable. has symptoms consistent with covid-19, as determined by investigator, with onset ≤10 days before randomization hospitalized for ≤72 hours with at least 1 of the following at randomization; patients meeting more than one criterion will be categorized in the most severely affected category: cohort 1a: with covid-19 symptoms but not requiring supplemental oxygen cohort 1: maintains o2 saturation >93% on low-flow oxygen as defined in the protocol cohort 2: high-intensity oxygen therapy without mechanical ventilation as defined in the protocol cohort 3: on mechanical ventilation key

key inclusion criteria: has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization and no alternative explanation for current clinical condition. a historical record of positive result from test conducted ≤72 hours prior to randomization is acceptable. has symptoms consistent with covid-19, as determined by investigator, with onset ≤10 days before randomization hospitalized for ≤72 hours with at least 1 of the following at randomization; patients meeting more than one criterion will be categorized in the most severely affected category: cohort 1a: with covid-19 symptoms but not requiring supplemental oxygen cohort 1: maintains o2 saturation >93% on low-flow oxygen as defined in the protocol cohort 2: high-intensity oxygen therapy without mechanical ventilation as defined in the protocol cohort 3: on mechanical ventilation key

key inclusion criteria: - has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization and no alternative explanation for current clinical condition. a historical record of positive result from test conducted ≤72 hours prior to randomization is acceptable. - has symptoms consistent with covid-19, as determined by investigator, with onset ≤10 days before randomization - hospitalized for ≤72 hours with at least 1 of the following at randomization; patients meeting more than one criterion will be categorized in the most severely affected category: 1. cohort 1a: with covid-19 symptoms but not requiring supplemental oxygen 2. cohort 1: maintains o2 saturation >93% on low-flow oxygen as defined in the protocol 3. cohort 2: high-intensity oxygen therapy without mechanical ventilation as defined in the protocol 4. cohort 3: on mechanical ventilation key

key inclusion criteria: - has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization and no alternative explanation for current clinical condition. a historical record of positive result from test conducted ≤72 hours prior to randomization is acceptable. - has symptoms consistent with covid-19, as determined by investigator, with onset ≤10 days before randomization - hospitalized for ≤72 hours with at least 1 of the following at randomization; patients meeting more than one criterion will be categorized in the most severely affected category: 1. cohort 1a: with covid-19 symptoms but not requiring supplemental oxygen 2. cohort 1: maintains o2 saturation >93% on low-flow oxygen as defined in the protocol 3. cohort 2: high-intensity oxygen therapy without mechanical ventilation as defined in the protocol 4. cohort 3: on mechanical ventilation key

key inclusion criteria: - has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization and no alternative explanation for current clinical condition. a historical record of positive result from test conducted ≤72 hours prior to randomization is acceptable. - has symptoms consistent with covid-19, as determined by investigator, with onset ≤10 days before randomization - hospitalized for covid-19 illness for ≤72 hours with at least 1 of the following at randomization; patients meeting more than one criterion will be categorized in the most severely affected category: 1. cohort 1a: with covid-19 symptoms but not requiring supplemental oxygen 2. cohort 1: maintains o2 saturation >93% on low-flow oxygen as defined in the protocol 3. cohort 2: high-intensity oxygen therapy without mechanical ventilation as defined in the protocol 4. cohort 3: on mechanical ventilation key

key inclusion criteria: - has sars-cov-2-positive antigen or molecular diagnostic test (by validated sars-cov-2 antigen, rt-pcr, or other molecular diagnostic assay, using an appropriate sample such as np, nasal, oropharyngeal [op], or saliva) ≤72 hours prior to randomization and no alternative explanation for current clinical condition. a historical record of positive result from test conducted ≤72 hours prior to randomization is acceptable. - has symptoms consistent with covid-19, as determined by investigator, with onset ≤10 days before randomization - hospitalized for covid-19 illness for ≤72 hours with at least 1 of the following at randomization; patients meeting more than one criterion will be categorized in the most severely affected category: 1. cohort 1a: with covid-19 symptoms but not requiring supplemental oxygen 2. cohort 1: maintains o2 saturation >93% on low-flow oxygen as defined in the protocol 3. cohort 2: high-intensity oxygen therapy without mechanical ventilation as defined in the protocol 4. cohort 3: on mechanical ventilation key