* have an oxygen saturation (spo2) \< 88% on room air at rest for 5 minutes or ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) \<= 200 mmhg at randomization. * requiring high-flow nasal cannula oxygen therapy/non-invasive or invasive mechanical ventilation/extracorporeal membrane oxygenation (ecmo) or anticipated impending need for high-flow nasal cannula oxygen therapy/non-invasive or invasive mechanical ventilation/ecmo. * prior treatment with a sars-cov-2 specific monoclonal antibody or convalescent covid-19 plasma.

* have an oxygen saturation (spo2) \< 88% on room air at rest for 5 minutes or ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) \<= 200 mmhg at randomization. * requiring high-flow nasal cannula oxygen therapy/non-invasive or invasive mechanical ventilation/extracorporeal membrane oxygenation (ecmo) or anticipated impending need for high-flow nasal cannula oxygen therapy/non-invasive or invasive mechanical ventilation/ecmo. * prior treatment with a sars-cov-2 specific monoclonal antibody or convalescent covid-19 plasma.

- have an oxygen saturation (spo2) < 88% on room air at rest for 5 minutes or ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) <= 200 mmhg at randomization. - requiring high-flow nasal cannula oxygen therapy/non-invasive or invasive mechanical ventilation/extracorporeal membrane oxygenation (ecmo) or anticipated impending need for high-flow nasal cannula oxygen therapy/non-invasive or invasive mechanical ventilation/ecmo. - prior treatment with a sars-cov-2 specific monoclonal antibody or convalescent covid-19 plasma.

- have an oxygen saturation (spo2) < 88% on room air at rest for 5 minutes or ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) <= 200 mmhg at randomization. - requiring high-flow nasal cannula oxygen therapy/non-invasive or invasive mechanical ventilation/extracorporeal membrane oxygenation (ecmo) or anticipated impending need for high-flow nasal cannula oxygen therapy/non-invasive or invasive mechanical ventilation/ecmo. - prior treatment with a sars-cov-2 specific monoclonal antibody or convalescent covid-19 plasma.

- have an oxygen saturation (spo2) < 88% on room air at rest for 5 minutes or ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) <= 200 mmhg at randomization. - requiring high-flow oxygen therapy/non-invasive or invasive mechanical ventilation/extracorporeal membrane oxygenation (ecmo) or anticipated impending need for high-flow oxygen therapy/non-invasive or invasive mechanical ventilation/ecmo. - prior treatment with a sars-cov-2 specific monoclonal antibody or convalescent covid-19 plasma.

- have an oxygen saturation (spo2) < 88% on room air at rest for 5 minutes or ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) <= 200 mmhg at randomization. - requiring high-flow oxygen therapy/non-invasive or invasive mechanical ventilation/extracorporeal membrane oxygenation (ecmo) or anticipated impending need for high-flow oxygen therapy/non-invasive or invasive mechanical ventilation/ecmo. - prior treatment with a sars-cov-2 specific monoclonal antibody or convalescent covid-19 plasma.

- have an oxygen saturation (spo2) < 88% on room air at rest for 5 minutes or ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) ≤ 200 mmhg at randomization. - requiring high-flow oxygen therapy/non-invasive or invasive mechanical ventilation/extracorporeal membrane oxygenation (ecmo) or anticipated impending need for high-flow oxygen therapy/non-invasive or invasive mechanical ventilation/ecmo. - prior treatment with a sars-cov-2 specific monoclonal antibody or convalescent covid-19 plasma.

- have an oxygen saturation (spo2) < 88% on room air at rest for 5 minutes or ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) ≤ 200 mmhg at randomization. - requiring high-flow oxygen therapy/non-invasive or invasive mechanical ventilation/extracorporeal membrane oxygenation (ecmo) or anticipated impending need for high-flow oxygen therapy/non-invasive or invasive mechanical ventilation/ecmo. - prior treatment with a sars-cov-2 specific monoclonal antibody or convalescent covid-19 plasma.