key inclusion criteria: - willing and able to provide written informed consent prior to performing study procedures (participants ≥ 18 years of age) or assent (participants ≥ 12 and < 18 years of age) prior to performing study procedures. for participants ≥ 12 and < 18 years of age, a parent or legal guardian willing and able to provide written informed consent prior to performing study procedures - severe acute respiratory syndrome coronavirus (sars-cov)-2 infection confirmed by polymerase chain reaction (pcr) test ≤ 4 days before randomization - currently hospitalized and requiring medical care for covid-19 - peripheral capillary oxygen saturation (spo2) > 94% on room air at screening - radiographic evidence of pulmonary infiltrates key

key inclusion criteria: - willing and able to provide written informed consent prior to performing study procedures (participants ≥ 18 years of age) or assent (participants ≥ 12 and < 18 years of age) prior to performing study procedures. for participants ≥ 12 and < 18 years of age, a parent or legal guardian willing and able to provide written informed consent prior to performing study procedures - severe acute respiratory syndrome coronavirus (sars-cov)-2 infection confirmed by polymerase chain reaction (pcr) test ≤ 4 days before randomization - currently hospitalized and requiring medical care for covid-19 - peripheral capillary oxygen saturation (spo2) > 94% on room air at screening - radiographic evidence of pulmonary infiltrates key