inclusion criteria: 1. is willing to provide informed consent (or has a legally authorized representative \[lar\] willing to provide informed consent) and is willing and able (or has an lar willing and able) to comply with the protocol required therapy, monitoring, and follow-up; 2. is a male or female aged ≥ 18 years; 3. has a covid-19 diagnosis confirmed by a documented, positive severe acute respiratory syndrome (sars) cov-2 reverse transcriptase polymerase chain reaction test (or equivalent test) immediately prior to or during the current hospitalization; 4. is hospitalized with severe to critical covid 19 within a 72-hour period prior to the screening visit and meeting the following characteristics: * diagnosed with ards based on the berlin criteria as follows: * respiratory symptoms developed within 1 week of a known clinical insult or new or worsening respiratory symptoms developed during the past week; * chest radiograph or computed tomography scan shows bilateral opacities not fully explained by pleural effusions, lobar or lung collapse, or pulmonary nodules; and * respiratory failure is not fully explained by cardiac failure or fluid overload; and * requiring at least 1 of the following: * endotracheal intubation and mechanical ventilation; * oxygen delivered by high flow nasal cannula (heated, humidified oxygen delivered via reinforced nasal cannula at flow rates \> 20 l/minute with a fraction of delivered oxygen ≥ 0.5); * non invasive positive pressure ventilation; or * clinical diagnosis of respiratory failure (ie, the clinical need for 1 of the preceding therapies, but preceding therapies are unable to be administered in the setting of resource limitations); 5. if female, is post-menopausal for at least 1 year, surgically sterile (documented by medical record), or a woman of childbearing potential (wcbp) who agrees to use a highly effective method of birth control (ie, method with a failure rate \< 1% per year) from enrollment until 30 days following the last dose of study drug. highly effective methods of birth control are defined as follows: complete sexual abstinence, intrauterine device, intrauterine hormone-releasing system, progestogen-only hormonal contraception (implant, injectable, or oral), and combined (estrogen and progestogen) contraception (oral, intravaginal, or transdermal); 6. if a wcbp, must have a negative serum human chorionic gonadotropin pregnancy test at the screening visit, and must agree to monthly urine pregnancy tests during the study; and 7. if male, must be surgically sterile for at least 1 year prior to the screening visit (documented by medical record), or must agree to use a double barrier approach (eg, condoms with spermicide) during sexual intercourse between the screening visit and at least 90 days after administration of the last dose of study drug. male patients must ensure that non pregnant female partners of childbearing potential comply with the contraception requirements in inclusion criterion 5.

inclusion criteria: 1. is willing to provide informed consent (or has a legally authorized representative \[lar\] willing to provide informed consent) and is willing and able (or has an lar willing and able) to comply with the protocol required therapy, monitoring, and follow-up; 2. is a male or female aged ≥ 18 years; 3. has a covid-19 diagnosis confirmed by a documented, positive severe acute respiratory syndrome (sars) cov-2 reverse transcriptase polymerase chain reaction test (or equivalent test) immediately prior to or during the current hospitalization; 4. is hospitalized with severe to critical covid 19 within a 72-hour period prior to the screening visit and meeting the following characteristics: * diagnosed with ards based on the berlin criteria as follows: * respiratory symptoms developed within 1 week of a known clinical insult or new or worsening respiratory symptoms developed during the past week; * chest radiograph or computed tomography scan shows bilateral opacities not fully explained by pleural effusions, lobar or lung collapse, or pulmonary nodules; and * respiratory failure is not fully explained by cardiac failure or fluid overload; and * requiring at least 1 of the following: * endotracheal intubation and mechanical ventilation; * oxygen delivered by high flow nasal cannula (heated, humidified oxygen delivered via reinforced nasal cannula at flow rates \> 20 l/minute with a fraction of delivered oxygen ≥ 0.5); * non invasive positive pressure ventilation; or * clinical diagnosis of respiratory failure (ie, the clinical need for 1 of the preceding therapies, but preceding therapies are unable to be administered in the setting of resource limitations); 5. if female, is post-menopausal for at least 1 year, surgically sterile (documented by medical record), or a woman of childbearing potential (wcbp) who agrees to use a highly effective method of birth control (ie, method with a failure rate \< 1% per year) from enrollment until 30 days following the last dose of study drug. highly effective methods of birth control are defined as follows: complete sexual abstinence, intrauterine device, intrauterine hormone-releasing system, progestogen-only hormonal contraception (implant, injectable, or oral), and combined (estrogen and progestogen) contraception (oral, intravaginal, or transdermal); 6. if a wcbp, must have a negative serum human chorionic gonadotropin pregnancy test at the screening visit, and must agree to monthly urine pregnancy tests during the study; and 7. if male, must be surgically sterile for at least 1 year prior to the screening visit (documented by medical record), or must agree to use a double barrier approach (eg, condoms with spermicide) during sexual intercourse between the screening visit and at least 90 days after administration of the last dose of study drug. male patients must ensure that non pregnant female partners of childbearing potential comply with the contraception requirements in inclusion criterion 5.

inclusion criteria: is willing to provide informed consent (or has a legally authorized representative [lar] willing to provide informed consent) and is willing and able (or has an lar willing and able) to comply with the protocol required therapy, monitoring, and follow-up; is a male or female aged ≥ 18 years; has a covid-19 diagnosis confirmed by a documented, positive severe acute respiratory syndrome (sars) cov-2 reverse transcriptase polymerase chain reaction test (or equivalent test) immediately prior to or during the current hospitalization; is hospitalized with severe to critical covid 19 within a 72-hour period prior to the screening visit and meeting the following characteristics: diagnosed with ards based on the berlin criteria as follows: respiratory symptoms developed within 1 week of a known clinical insult or new or worsening respiratory symptoms developed during the past week; chest radiograph or computed tomography scan shows bilateral opacities not fully explained by pleural effusions, lobar or lung collapse, or pulmonary nodules; and respiratory failure is not fully explained by cardiac failure or fluid overload; and requiring at least 1 of the following: endotracheal intubation and mechanical ventilation; oxygen delivered by high flow nasal cannula (heated, humidified oxygen delivered via reinforced nasal cannula at flow rates > 20 l/minute with a fraction of delivered oxygen ≥ 0.5); non invasive positive pressure ventilation; or clinical diagnosis of respiratory failure (ie, the clinical need for 1 of the preceding therapies, but preceding therapies are unable to be administered in the setting of resource limitations); if female, is post-menopausal for at least 1 year, surgically sterile (documented by medical record), or a woman of childbearing potential (wcbp) who agrees to use a highly effective method of birth control (ie, method with a failure rate < 1% per year) from enrollment until 30 days following the last dose of study drug. highly effective methods of birth control are defined as follows: complete sexual abstinence, intrauterine device, intrauterine hormone-releasing system, progestogen-only hormonal contraception (implant, injectable, or oral), and combined (estrogen and progestogen) contraception (oral, intravaginal, or transdermal); if a wcbp, must have a negative serum human chorionic gonadotropin pregnancy test at the screening visit, and must agree to monthly urine pregnancy tests during the study; and if male, must be surgically sterile for at least 1 year prior to the screening visit (documented by medical record), or must agree to use a double barrier approach (eg, condoms with spermicide) during sexual intercourse between the screening visit and at least 90 days after administration of the last dose of study drug. male patients must ensure that non pregnant female partners of childbearing potential comply with the contraception requirements in inclusion criterion 5.

inclusion criteria: is willing to provide informed consent (or has a legally authorized representative [lar] willing to provide informed consent) and is willing and able (or has an lar willing and able) to comply with the protocol required therapy, monitoring, and follow-up; is a male or female aged ≥ 18 years; has a covid-19 diagnosis confirmed by a documented, positive severe acute respiratory syndrome (sars) cov-2 reverse transcriptase polymerase chain reaction test (or equivalent test) immediately prior to or during the current hospitalization; is hospitalized with severe to critical covid 19 within a 72-hour period prior to the screening visit and meeting the following characteristics: diagnosed with ards based on the berlin criteria as follows: respiratory symptoms developed within 1 week of a known clinical insult or new or worsening respiratory symptoms developed during the past week; chest radiograph or computed tomography scan shows bilateral opacities not fully explained by pleural effusions, lobar or lung collapse, or pulmonary nodules; and respiratory failure is not fully explained by cardiac failure or fluid overload; and requiring at least 1 of the following: endotracheal intubation and mechanical ventilation; oxygen delivered by high flow nasal cannula (heated, humidified oxygen delivered via reinforced nasal cannula at flow rates > 20 l/minute with a fraction of delivered oxygen ≥ 0.5); non invasive positive pressure ventilation; or clinical diagnosis of respiratory failure (ie, the clinical need for 1 of the preceding therapies, but preceding therapies are unable to be administered in the setting of resource limitations); if female, is post-menopausal for at least 1 year, surgically sterile (documented by medical record), or a woman of childbearing potential (wcbp) who agrees to use a highly effective method of birth control (ie, method with a failure rate < 1% per year) from enrollment until 30 days following the last dose of study drug. highly effective methods of birth control are defined as follows: complete sexual abstinence, intrauterine device, intrauterine hormone-releasing system, progestogen-only hormonal contraception (implant, injectable, or oral), and combined (estrogen and progestogen) contraception (oral, intravaginal, or transdermal); if a wcbp, must have a negative serum human chorionic gonadotropin pregnancy test at the screening visit, and must agree to monthly urine pregnancy tests during the study; and if male, must be surgically sterile for at least 1 year prior to the screening visit (documented by medical record), or must agree to use a double barrier approach (eg, condoms with spermicide) during sexual intercourse between the screening visit and at least 90 days after administration of the last dose of study drug. male patients must ensure that non pregnant female partners of childbearing potential comply with the contraception requirements in inclusion criterion 5.

inclusion criteria: 1. is willing to provide informed consent (or has a legally authorized representative [lar] willing to provide informed consent) and is willing and able (or has an lar willing and able) to comply with the protocol required therapy, monitoring, and follow-up; 2. is a male or female aged ≥ 18 years; 3. has a covid-19 diagnosis confirmed by a documented, positive severe acute respiratory syndrome (sars) cov-2 reverse transcriptase polymerase chain reaction test (or equivalent test) immediately prior to or during the current hospitalization; 4. is hospitalized with severe to critical covid 19 within a 72-hour period prior to the screening visit and meeting the following characteristics: - diagnosed with ards based on the berlin criteria as follows: - respiratory symptoms developed within 1 week of a known clinical insult or new or worsening respiratory symptoms developed during the past week; - chest radiograph or computed tomography scan shows bilateral opacities not fully explained by pleural effusions, lobar or lung collapse, or pulmonary nodules; and - respiratory failure is not fully explained by cardiac failure or fluid overload; and - requiring at least 1 of the following: - endotracheal intubation and mechanical ventilation; - oxygen delivered by high flow nasal cannula (heated, humidified oxygen delivered via reinforced nasal cannula at flow rates > 20 l/minute with a fraction of delivered oxygen ≥ 0.5); - non invasive positive pressure ventilation; or - clinical diagnosis of respiratory failure (ie, the clinical need for 1 of the preceding therapies, but preceding therapies are unable to be administered in the setting of resource limitations); 5. if female, is post-menopausal for at least 1 year, surgically sterile (documented by medical record), or a woman of childbearing potential (wcbp) who agrees to use a highly effective method of birth control (ie, method with a failure rate < 1% per year) from enrollment until 30 days following the last dose of study drug. highly effective methods of birth control are defined as follows: complete sexual abstinence, intrauterine device, intrauterine hormone-releasing system, progestogen-only hormonal contraception (implant, injectable, or oral), and combined (estrogen and progestogen) contraception (oral, intravaginal, or transdermal); 6. if a wcbp, must have a negative serum human chorionic gonadotropin pregnancy test at the screening visit, and must agree to monthly urine pregnancy tests during the study; and 7. if male, must be surgically sterile for at least 1 year prior to the screening visit (documented by medical record), or must agree to use a double barrier approach (eg, condoms with spermicide) during sexual intercourse between the screening visit and at least 90 days after administration of the last dose of study drug. male patients must ensure that non pregnant female partners of childbearing potential comply with the contraception requirements in inclusion criterion 5.

inclusion criteria: 1. is willing to provide informed consent (or has a legally authorized representative [lar] willing to provide informed consent) and is willing and able (or has an lar willing and able) to comply with the protocol required therapy, monitoring, and follow-up; 2. is a male or female aged ≥ 18 years; 3. has a covid-19 diagnosis confirmed by a documented, positive severe acute respiratory syndrome (sars) cov-2 reverse transcriptase polymerase chain reaction test (or equivalent test) immediately prior to or during the current hospitalization; 4. is hospitalized with severe to critical covid 19 within a 72-hour period prior to the screening visit and meeting the following characteristics: - diagnosed with ards based on the berlin criteria as follows: - respiratory symptoms developed within 1 week of a known clinical insult or new or worsening respiratory symptoms developed during the past week; - chest radiograph or computed tomography scan shows bilateral opacities not fully explained by pleural effusions, lobar or lung collapse, or pulmonary nodules; and - respiratory failure is not fully explained by cardiac failure or fluid overload; and - requiring at least 1 of the following: - endotracheal intubation and mechanical ventilation; - oxygen delivered by high flow nasal cannula (heated, humidified oxygen delivered via reinforced nasal cannula at flow rates > 20 l/minute with a fraction of delivered oxygen ≥ 0.5); - non invasive positive pressure ventilation; or - clinical diagnosis of respiratory failure (ie, the clinical need for 1 of the preceding therapies, but preceding therapies are unable to be administered in the setting of resource limitations); 5. if female, is post-menopausal for at least 1 year, surgically sterile (documented by medical record), or a woman of childbearing potential (wcbp) who agrees to use a highly effective method of birth control (ie, method with a failure rate < 1% per year) from enrollment until 30 days following the last dose of study drug. highly effective methods of birth control are defined as follows: complete sexual abstinence, intrauterine device, intrauterine hormone-releasing system, progestogen-only hormonal contraception (implant, injectable, or oral), and combined (estrogen and progestogen) contraception (oral, intravaginal, or transdermal); 6. if a wcbp, must have a negative serum human chorionic gonadotropin pregnancy test at the screening visit, and must agree to monthly urine pregnancy tests during the study; and 7. if male, must be surgically sterile for at least 1 year prior to the screening visit (documented by medical record), or must agree to use a double barrier approach (eg, condoms with spermicide) during sexual intercourse between the screening visit and at least 90 days after administration of the last dose of study drug. male patients must ensure that non pregnant female partners of childbearing potential comply with the contraception requirements in inclusion criterion 5.