Phase II 1. At least 18 years of age or older 2. Clinically evident or otherwise confirmed severe pneumonia as evidenced by at least one of the following criteria: 3. Chest X-ray or computed tomography (CT) scan or magnetic resonance imaging (MRI) with pulmonary infiltrates consistent with pneumonia 4. Clinical history in past 14 days of newly developed severe shortness of breath (> 29 breaths / minute) in the absence of oxygen supply or spontaneous peripheral oxygenation ≤ 92 with need for oxygen supply, or need for non-invasive or invasive ventilation (in conjunction with a positive test for SARS-CoV-2 infection) 5. Oxygenation index at time of enrollment (PaO2 / FiO2) ≤ 250 and ≥ 100 in supine position 6. SARS-CoV-2 infection confirmation (tested positive in last 14 days or test results to be obtained within 24h after enrollment, both with locally available test system). 7. No use OR stop of any corticosteroid treatment at time point of enrollment (topical treatment and systemic dose of ≤ 10mg prednisone / day equivalent allowed) Phase III 1. At least 18 years of age or older 2. Patient on invasive mechanical ventilation (but not more than 48h post intubation at time point of randomization) 3. Patients with a PaO2 / FiO2 ratio of < 200 and > 60 at randomization (one representative measurement within 6h before randomization) 4. SARS-CoV-2 infection confirmation (tested positive in last 14 days before randomization with locally available test system)

Phase II 1. At least 18 years of age or older 2. Clinically evident or otherwise confirmed severe pneumonia as evidenced by at least one of the following criteria: 3. Chest X-ray or computed tomography (CT) scan or magnetic resonance imaging (MRI) with pulmonary infiltrates consistent with pneumonia 4. Clinical history in past 14 days of newly developed severe shortness of breath (> 29 breaths / minute) in the absence of oxygen supply or spontaneous peripheral oxygenation ≤ 92 with need for oxygen supply, or need for non-invasive or invasive ventilation (in conjunction with a positive test for SARS-CoV-2 infection) 5. Oxygenation index at time of enrollment (PaO2 / FiO2) ≤ 250 and ≥ 100 in supine position 6. SARS-CoV-2 infection confirmation (tested positive in last 14 days or test results to be obtained within 24h after enrollment, both with locally available test system). 7. No use OR stop of any corticosteroid treatment at time point of enrollment (topical treatment and systemic dose of ≤ 10mg prednisone / day equivalent allowed) Phase III 1. At least 18 years of age or older 2. Patient on invasive mechanical ventilation (but not more than 48h post intubation at time point of randomization) 3. Patients with a PaO2 / FiO2 ratio of < 200 and > 60 at randomization (one representative measurement within 6h before randomization) 4. SARS-CoV-2 infection confirmation (tested positive in last 14 days before randomization with locally available test system)

Phase II 1. At least 18 years of age or older 2. Clinically evident or otherwise confirmed severe pneumonia as evidenced by at least one of the following criteria: 3. Chest X-ray or computed tomography (CT) scan or magnetic resonance imaging (MRI) with pulmonary infiltrates consistent with pneumonia 4. Clinical history in past 14 days of newly developed severe shortness of breath (> 29 breaths / minute) in the absence of oxygen supply or spontaneous peripheral oxygenation ≤ 92 with need for oxygen supply, or need for non-invasive or invasive ventilation (in conjunction with a positive test for SARS-CoV-2 infection) 5. Oxygenation index at time of enrollment (PaO2 / FiO2) ≤ 250 and ≥ 100 in supine position 6. SARS-CoV-2 infection confirmation (tested positive in last 14 days or test results to be obtained within 24h after enrollment, both with locally available test system). 7. No use OR stop of any corticosteroid treatment at time point of enrollment (topical treatment and systemic dose of ≤ 10mg prednisone / day equivalent allowed) Phase III 1. At least 18 years of age or older 2. Patient on invasive mechanical ventilation (but not more than 48h post intubation at time point of first IMP randomization) 3. Patients with a PaO2 / FiO2 ratio of < 200 and > 60 at randomization (one representative measurement within 6h before randomization) 4. SARS-CoV-2 infection confirmation (tested positive in last 14 days before randomization with locally available test system)

Phase II 1. At least 18 years of age or older 2. Clinically evident or otherwise confirmed severe pneumonia as evidenced by at least one of the following criteria: 3. Chest X-ray or computed tomography (CT) scan or magnetic resonance imaging (MRI) with pulmonary infiltrates consistent with pneumonia 4. Clinical history in past 14 days of newly developed severe shortness of breath (> 29 breaths / minute) in the absence of oxygen supply or spontaneous peripheral oxygenation ≤ 92 with need for oxygen supply, or need for non-invasive or invasive ventilation (in conjunction with a positive test for SARS-CoV-2 infection) 5. Oxygenation index at time of enrollment (PaO2 / FiO2) ≤ 250 and ≥ 100 in supine position 6. SARS-CoV-2 infection confirmation (tested positive in last 14 days or test results to be obtained within 24h after enrollment, both with locally available test system). 7. No use OR stop of any corticosteroid treatment at time point of enrollment (topical treatment and systemic dose of ≤ 10mg prednisone / day equivalent allowed) Phase III 1. At least 18 years of age or older 2. Patient on invasive mechanical ventilation (but not more than 48h post intubation at time point of first IMP randomization) 3. Patients with a PaO2 / FiO2 ratio of < 200 and > 60 at randomization (one representative measurement within 6h before randomization) 4. SARS-CoV-2 infection confirmation (tested positive in last 14 days before randomization with locally available test system)

Phase II 1. At least 18 years of age or older 2. Clinically evident or otherwise confirmed severe pneumonia as evidenced by at least one of the following criteria: 3. Chest X-ray or computed tomography (CT) scan or magnetic resonance imaging (MRI) with pulmonary infiltrates consistent with pneumonia 4. Clinical history in past 14 days of newly developed severe shortness of breath (> 29 breaths / minute) in the absence of oxygen supply or spontaneous peripheral oxygenation ≤ 92 with need for oxygen supply, or need for non-invasive or invasive ventilation (in conjunction with a positive test for SARS-CoV-2 infection) 5. Oxygenation index at time of enrollment (PaO2 / FiO2) ≤ 250 and ≥ 100 in supine position 6. SARS-CoV-2 infection confirmation (tested positive in last 14 days or test results to be obtained within 24h after enrollment, both with locally available test system). 7. No use OR stop of any corticosteroid treatment at time point of enrollment (topical treatment and systemic dose of ≤ 10mg prednisone / day equivalent allowed) Phase III 1. At least 18 years of age or older 2. Patient on invasive mechanical ventilation (but not more than 48h post intubation at time point of randomization) 3. Patients with a PaO2 / FiO2 ratio of < 200 and > 60 at randomization (one representative measurement within 6h before randomization) 4. SARS-CoV-2 infection confirmation (tested positive in last 14 days before randomization with locally available test system)

Phase II 1. At least 18 years of age or older 2. Clinically evident or otherwise confirmed severe pneumonia as evidenced by at least one of the following criteria: 3. Chest X-ray or computed tomography (CT) scan or magnetic resonance imaging (MRI) with pulmonary infiltrates consistent with pneumonia 4. Clinical history in past 14 days of newly developed severe shortness of breath (> 29 breaths / minute) in the absence of oxygen supply or spontaneous peripheral oxygenation ≤ 92 with need for oxygen supply, or need for non-invasive or invasive ventilation (in conjunction with a positive test for SARS-CoV-2 infection) 5. Oxygenation index at time of enrollment (PaO2 / FiO2) ≤ 250 and ≥ 100 in supine position 6. SARS-CoV-2 infection confirmation (tested positive in last 14 days or test results to be obtained within 24h after enrollment, both with locally available test system). 7. No use OR stop of any corticosteroid treatment at time point of enrollment (topical treatment and systemic dose of ≤ 10mg prednisone / day equivalent allowed) Phase III 1. At least 18 years of age or older 2. Patient on invasive mechanical ventilation (but not more than 48h post intubation at time point of randomization) 3. Patients with a PaO2 / FiO2 ratio of < 200 and > 60 at randomization (one representative measurement within 6h before randomization) 4. SARS-CoV-2 infection confirmation (tested positive in last 14 days before randomization with locally available test system)