key inclusion criteria: - positive result of a molecular rt-qpcr diagnostic test or sars-cov-2 rna result from a clinical specimen deemed clinically associated with the current episode of illness, warranting hospital admission as per investigator's judgement, or previously hospitalized (central and/or local laboratory covid-19 test results are accepted from any biological material source) - hospitalization for covid-19 respiratory disease and treated with supplemental oxygen (including mv, ecmo or any other means of oxygen administration) in hospital for at least 1 day - covid-19 pneumonia findings on imaging (chest x-ray or ct scan) with a minimum of two lung lobes involvement - able to bear weight and ambulate a minimum of 10 m distance (use of inhaled oxygen permitted) - shortness of breath ≥ grade 3 on mbds dyspnea scale and not requiring mv, ecmo, niv, and/or hfno (nasal o2 is allowed) for at least 72 hours before screening key

key inclusion criteria: - positive result of a molecular rt-qpcr diagnostic test or sars-cov-2 rna result from a clinical specimen deemed clinically associated with the current episode of illness, warranting hospital admission as per investigator's judgement, or previously hospitalized (central and/or local laboratory covid-19 test results are accepted from any biological material source) - hospitalization for covid-19 respiratory disease and treated with supplemental oxygen (including mv, ecmo or any other means of oxygen administration) in hospital for at least 1 day - covid-19 pneumonia findings on imaging (chest x-ray or ct scan) with a minimum of two lung lobes involvement - able to bear weight and ambulate a minimum of 10 m distance (use of inhaled oxygen permitted) - shortness of breath ≥ grade 3 on mbds dyspnea scale and not requiring mv, ecmo, niv, and/or hfno (nasal o2 is allowed) for at least 72 hours before screening key

key inclusion criteria: - hospitalization for covid-19 respiratory disease (with positive result of a molecular rt-qpcr diagnostic test or sars-cov-2 rna result) for at least 1-day within the last 42 days prior to screening, and requiring at least one of the listed treatment modalities: mv, ecmo, niv, hfno during hospitalization - covid-19 pneumonia findings on imaging (chest x-ray or ct scan) with a minimum of two lung lobes involvement - able to bear weight and ambulate a minimum of 10 m distance (use of inhaled oxygen permitted) - shortness of breath ≥ grade 3 on mbds dyspnea scale and not requiring mv, ecmo, niv, and/or hfno (nasal o2 is allowed) for at least 72 hours before screening key

key inclusion criteria: - hospitalization for covid-19 respiratory disease (with positive result of a molecular rt-qpcr diagnostic test or sars-cov-2 rna result) for at least 1-day within the last 42 days prior to screening, and requiring at least one of the listed treatment modalities: mv, ecmo, niv, hfno during hospitalization - covid-19 pneumonia findings on imaging (chest x-ray or ct scan) with a minimum of two lung lobes involvement - able to bear weight and ambulate a minimum of 10 m distance (use of inhaled oxygen permitted) - shortness of breath ≥ grade 3 on mbds dyspnea scale and not requiring mv, ecmo, niv, and/or hfno (nasal o2 is allowed) for at least 72 hours before screening key