inclusion criteria: * able and willing to give signed informed consent * patients hospitalized with a presumed diagnosis of pneumonia of \< 48 hours duration requiring supplemental oxygen therapy. eligible patients include those hospitalized for a separate non-infectious reason who subsequently develop a presumed pneumonia; * radiologic imaging (chest x-ray, ct scan, etc.) evidence of pulmonary involvement with new and persistent or progressive and persistent infiltrate, consolidation or cavitation. signs and symptoms: at least 1 of the following signs: * respiratory rate \> 30 breaths/min; * fever (\> 38.0ºc or \> 100.4o f); * leukopenia (≤ 4,000 wbc/mm3 or leukocytosis (≥ 12,000 wbc/mm3); * adults ≥ 70 years of age; altered mental status with no other recognized cause; and at least 1 of the following symptoms: * new onset of purulent sputum or change in character of sputum or increased respiratory secretions; * new onset or worsening cough, or dyspnea, or tachypnea; * rales or bronchial breath sounds; * female patients of reproductive potential must be on an effective contraceptive method

inclusion criteria: * able and willing to give signed informed consent * patients hospitalized with a presumed diagnosis of pneumonia of \< 48 hours duration requiring supplemental oxygen therapy. eligible patients include those hospitalized for a separate non-infectious reason who subsequently develop a presumed pneumonia; * radiologic imaging (chest x-ray, ct scan, etc.) evidence of pulmonary involvement with new and persistent or progressive and persistent infiltrate, consolidation or cavitation. signs and symptoms: at least 1 of the following signs: * respiratory rate \> 30 breaths/min; * fever (\> 38.0ºc or \> 100.4o f); * leukopenia (≤ 4,000 wbc/mm3 or leukocytosis (≥ 12,000 wbc/mm3); * adults ≥ 70 years of age; altered mental status with no other recognized cause; and at least 1 of the following symptoms: * new onset of purulent sputum or change in character of sputum or increased respiratory secretions; * new onset or worsening cough, or dyspnea, or tachypnea; * rales or bronchial breath sounds; * female patients of reproductive potential must be on an effective contraceptive method

inclusion criteria: able and willing to give signed informed consent patients hospitalized with a presumed diagnosis of pneumonia of < 48 hours duration requiring supplemental oxygen therapy. eligible patients include those hospitalized for a separate non-infectious reason who subsequently develop a presumed pneumonia; radiologic imaging (chest x-ray, ct scan, etc.) evidence of pulmonary involvement with new and persistent or progressive and persistent infiltrate, consolidation or cavitation. signs and symptoms: at least 1 of the following signs: respiratory rate > 30 breaths/min; fever (> 38.0ºc or > 100.4o f); leukopenia (≤ 4,000 wbc/mm3 or leukocytosis (≥ 12,000 wbc/mm3); adults ≥ 70 years of age; altered mental status with no other recognized cause; and at least 1 of the following symptoms: new onset of purulent sputum or change in character of sputum or increased respiratory secretions; new onset or worsening cough, or dyspnea, or tachypnea; rales or bronchial breath sounds; female patients of reproductive potential must be on an effective contraceptive method

inclusion criteria: able and willing to give signed informed consent patients hospitalized with a presumed diagnosis of pneumonia of < 48 hours duration requiring supplemental oxygen therapy. eligible patients include those hospitalized for a separate non-infectious reason who subsequently develop a presumed pneumonia; radiologic imaging (chest x-ray, ct scan, etc.) evidence of pulmonary involvement with new and persistent or progressive and persistent infiltrate, consolidation or cavitation. signs and symptoms: at least 1 of the following signs: respiratory rate > 30 breaths/min; fever (> 38.0ºc or > 100.4o f); leukopenia (≤ 4,000 wbc/mm3 or leukocytosis (≥ 12,000 wbc/mm3); adults ≥ 70 years of age; altered mental status with no other recognized cause; and at least 1 of the following symptoms: new onset of purulent sputum or change in character of sputum or increased respiratory secretions; new onset or worsening cough, or dyspnea, or tachypnea; rales or bronchial breath sounds; female patients of reproductive potential must be on an effective contraceptive method

inclusion criteria: able and willing to give signed informed consent hospitalized less than 48 hours with pneumonia and confirmed covid-19 disease meet the criteria for severe covid_19 disease at randomization defined as patients that have one or more of the following: oxygen saturation as detected by pulse oximeter (spo2) < 94% on room air at sea level ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) < 300 mm hg respiratory rate > 30 breaths/min lung infiltrates involving > 50% of lung parenchyma score of 5 or 6 on the who covid-19 10-point clinical progression scale (cps) at randomization female patients of reproductive potential must be on an effective contraceptive method

inclusion criteria: able and willing to give signed informed consent hospitalized less than 48 hours with pneumonia and confirmed covid-19 disease meet the criteria for severe covid_19 disease at randomization defined as patients that have one or more of the following: oxygen saturation as detected by pulse oximeter (spo2) < 94% on room air at sea level ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (pao2/fio2) < 300 mm hg respiratory rate > 30 breaths/min lung infiltrates involving > 50% of lung parenchyma score of 5 or 6 on the who covid-19 10-point clinical progression scale (cps) at randomization female patients of reproductive potential must be on an effective contraceptive method