inclusion criteria * 18 years or older * patient has sars-cov-2 (covid-19) confirmed by real-time reverse transcription polymerase chain reaction (rt-pcr) assay or other diagnostic test * patient requiring mechanical ventilatory support with moderate to severe ards as determined by the following criteria (adapted from the berlin criteria) * bilateral opacities must be present on a chest radiograph or computerized tomographic (ct) scan. these opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, or pulmonary nodules. * respiratory failure not fully explained by cardiac failure or fluid overload. * moderate to severe impairment of oxygenation must be present, as defined by the ratio of arterial oxygen tension to fraction of inspired oxygen (pao2/fio2). the severity of the hypoxemia defines the severity of the ards: * moderate ards: pao2/fio2 \>100 mmhg and ≤200 mmhg, on ventilator settings that include peep ≥5 cm h2o or * severe ards: pao2/fio2 ≤100 mmhg on ventilator settings that include peep ≥5 cm h2o * high sensitivity c-reactive protein (hs-crp) or crp serum level \>4.0 mg/dl * acute physiologic and chronic health evaluation (apache iv) score \>5 * creatinine clearance of ≥ 30 ml/minute or a creatinine clearance of 20-29 ml/minute with urine output of ≥0.3 mls/kg/hour over the last 8 hours or ≥500 mls over the last 24 hours * the patient or his/her legally authorized representative (lar) is able to provide informed consent exclusion criteria * currently receiving extracorporeal membrane oxygenation (ecmo) or high frequency oscillatory ventilation (hfov) * females who are pregnant or lactating * patients with established positive bacterial blood cultures prior to enrollment or suspicion of superimposed bacterial pneumonia * patients with bmi \>55 * patients with untreated hiv infection * patients with malignancy who are within 12 months of active treatment with any chemotherapy, radiation or immunotherapy. * patients who have been intubated for more than 72 hours in total at the time of randomization * creatinine clearance less than 20 ml/minute or receiving renal replacement therapy * lfts (isolated alt or ast) \> 8x upper limit of normal or \> 5x upper limit of normal in the setting of other liver function abnormalities (i.e., total bilirubin ≥ 2x upper limit of normal) * known hypersensitivity to dmso or to porcine or bovine proteins * history of prior respiratory disease with requirement for supplemental oxygen * any end-stage organ disease which in the opinion of the investigator may possibly affect the safety of remestemcel-l treatment * receiving an investigational cellular therapy agent

inclusion criteria * 18 years or older * patient has sars-cov-2 (covid-19) confirmed by real-time reverse transcription polymerase chain reaction (rt-pcr) assay or other diagnostic test * patient requiring mechanical ventilatory support with moderate to severe ards as determined by the following criteria (adapted from the berlin criteria) * bilateral opacities must be present on a chest radiograph or computerized tomographic (ct) scan. these opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, or pulmonary nodules. * respiratory failure not fully explained by cardiac failure or fluid overload. * moderate to severe impairment of oxygenation must be present, as defined by the ratio of arterial oxygen tension to fraction of inspired oxygen (pao2/fio2). the severity of the hypoxemia defines the severity of the ards: * moderate ards: pao2/fio2 \>100 mmhg and ≤200 mmhg, on ventilator settings that include peep ≥5 cm h2o or * severe ards: pao2/fio2 ≤100 mmhg on ventilator settings that include peep ≥5 cm h2o * high sensitivity c-reactive protein (hs-crp) or crp serum level \>4.0 mg/dl * acute physiologic and chronic health evaluation (apache iv) score \>5 * creatinine clearance of ≥ 30 ml/minute or a creatinine clearance of 20-29 ml/minute with urine output of ≥0.3 mls/kg/hour over the last 8 hours or ≥500 mls over the last 24 hours * the patient or his/her legally authorized representative (lar) is able to provide informed consent exclusion criteria * currently receiving extracorporeal membrane oxygenation (ecmo) or high frequency oscillatory ventilation (hfov) * females who are pregnant or lactating * patients with established positive bacterial blood cultures prior to enrollment or suspicion of superimposed bacterial pneumonia * patients with bmi \>55 * patients with untreated hiv infection * patients with malignancy who are within 12 months of active treatment with any chemotherapy, radiation or immunotherapy. * patients who have been intubated for more than 72 hours in total at the time of randomization * creatinine clearance less than 20 ml/minute or receiving renal replacement therapy * lfts (isolated alt or ast) \> 8x upper limit of normal or \> 5x upper limit of normal in the setting of other liver function abnormalities (i.e., total bilirubin ≥ 2x upper limit of normal) * known hypersensitivity to dmso or to porcine or bovine proteins * history of prior respiratory disease with requirement for supplemental oxygen * any end-stage organ disease which in the opinion of the investigator may possibly affect the safety of remestemcel-l treatment * receiving an investigational cellular therapy agent

inclusion criteria - 18 years or older - patient has sars-cov-2 (covid-19) confirmed by real-time reverse transcription polymerase chain reaction (rt-pcr) assay or other diagnostic test - patient requiring mechanical ventilatory support with moderate to severe ards as determined by the following criteria (adapted from the berlin criteria) - bilateral opacities must be present on a chest radiograph or computerized tomographic (ct) scan. these opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, or pulmonary nodules. - respiratory failure not fully explained by cardiac failure or fluid overload. - moderate to severe impairment of oxygenation must be present, as defined by the ratio of arterial oxygen tension to fraction of inspired oxygen (pao2/fio2). the severity of the hypoxemia defines the severity of the ards: - moderate ards: pao2/fio2 >100 mmhg and ≤200 mmhg, on ventilator settings that include peep ≥5 cm h2o or - severe ards: pao2/fio2 ≤100 mmhg on ventilator settings that include peep ≥5 cm h2o - high sensitivity c-reactive protein (hs-crp) or crp serum level >4.0 mg/dl - acute physiologic and chronic health evaluation (apache iv) score >5 - creatinine clearance of ≥ 30 ml/minute or a creatinine clearance of 20-29 ml/minute with urine output of ≥0.3 mls/kg/hour over the last 8 hours or ≥500 mls over the last 24 hours - the patient or his/her legally authorized representative (lar) is able to provide informed consent exclusion criteria - currently receiving extracorporeal membrane oxygenation (ecmo) or high frequency oscillatory ventilation (hfov) - females who are pregnant or lactating - patients with established positive bacterial blood cultures prior to enrollment or suspicion of superimposed bacterial pneumonia - patients with bmi >55 - patients with untreated hiv infection - patients with malignancy who are within 12 months of active treatment with any chemotherapy, radiation or immunotherapy. - patients who have been intubated for more than 72 hours in total at the time of randomization - creatinine clearance less than 20 ml/minute or receiving renal replacement therapy - lfts (isolated alt or ast) > 8x upper limit of normal or > 5x upper limit of normal in the setting of other liver function abnormalities (i.e., total bilirubin ≥ 2x upper limit of normal) - known hypersensitivity to dmso or to porcine or bovine proteins - history of prior respiratory disease with requirement for supplemental oxygen - any end-stage organ disease which in the opinion of the investigator may possibly affect the safety of remestemcel-l treatment - receiving an investigational cellular therapy agent

inclusion criteria - 18 years or older - patient has sars-cov-2 (covid-19) confirmed by real-time reverse transcription polymerase chain reaction (rt-pcr) assay or other diagnostic test - patient requiring mechanical ventilatory support with moderate to severe ards as determined by the following criteria (adapted from the berlin criteria) - bilateral opacities must be present on a chest radiograph or computerized tomographic (ct) scan. these opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, or pulmonary nodules. - respiratory failure not fully explained by cardiac failure or fluid overload. - moderate to severe impairment of oxygenation must be present, as defined by the ratio of arterial oxygen tension to fraction of inspired oxygen (pao2/fio2). the severity of the hypoxemia defines the severity of the ards: - moderate ards: pao2/fio2 >100 mmhg and ≤200 mmhg, on ventilator settings that include peep ≥5 cm h2o or - severe ards: pao2/fio2 ≤100 mmhg on ventilator settings that include peep ≥5 cm h2o - high sensitivity c-reactive protein (hs-crp) or crp serum level >4.0 mg/dl - acute physiologic and chronic health evaluation (apache iv) score >5 - creatinine clearance of ≥ 30 ml/minute or a creatinine clearance of 20-29 ml/minute with urine output of ≥0.3 mls/kg/hour over the last 8 hours or ≥500 mls over the last 24 hours - the patient or his/her legally authorized representative (lar) is able to provide informed consent exclusion criteria - currently receiving extracorporeal membrane oxygenation (ecmo) or high frequency oscillatory ventilation (hfov) - females who are pregnant or lactating - patients with established positive bacterial blood cultures prior to enrollment or suspicion of superimposed bacterial pneumonia - patients with bmi >55 - patients with untreated hiv infection - patients with malignancy who are within 12 months of active treatment with any chemotherapy, radiation or immunotherapy. - patients who have been intubated for more than 72 hours in total at the time of randomization - creatinine clearance less than 20 ml/minute or receiving renal replacement therapy - lfts (isolated alt or ast) > 8x upper limit of normal or > 5x upper limit of normal in the setting of other liver function abnormalities (i.e., total bilirubin ≥ 2x upper limit of normal) - known hypersensitivity to dmso or to porcine or bovine proteins - history of prior respiratory disease with requirement for supplemental oxygen - any end-stage organ disease which in the opinion of the investigator may possibly affect the safety of remestemcel-l treatment - receiving an investigational cellular therapy agent

inclusion criteria - 18 years or older - patient has coronavirus disease covid-19 confirmed by real-time reverse transcription polymerase chain reaction (rt-pcr) assay or other diagnostic test - patient requiring mechanical ventilatory support with moderate to severe ards as determined by the following criteria (adapted from the berlin criteria) - bilateral opacities must be present on a chest radiograph or computed tomographic (ct) scan. these opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, or pulmonary nodules. - respiratory failure not fully explained by cardiac failure or fluid overload. - moderate to severe impairment of oxygenation must be present, as defined by the ratio of arterial oxygen tension to fraction of inspired oxygen (pao2/fio2). the severity of the hypoxemia defines the severity of the ards: - moderate ards: pao2/fio2 >100 mmhg and ≤200 mmhg, on ventilator settings that include peep ≥5 cm h2o or - severe ards: pao2/fio2 ≤100 mmhg on ventilator settings that include peep ≥5 cm h2o - high sensitivity c-reactive protein (hs-crp) serum level >4.0 mg/dl - acute physiologic and chronic health evaluation (apache iv) score >5 - the patient or his/her legally authorized representative (lar) is able to provide informed consent exclusion criteria - currently receiving extracorporeal membrane oxygenation (ecmo) or high frequency oscillatory ventilation (hfov) - females who are pregnant or lactating - patients with established positive bacterial blood cultures prior to enrollment or suspicion of superimposed bacterial pneumonia - patients with untreated hiv infection - patients who have been intubated for more than 72 hours - creatinine clearance less than 30 ml/minute - lfts (alt or ast) > 5x normal - known hypersensitivity to dmso or to porcine or bovine proteins - history of prior respiratory disease with requirement for supplemental oxygen - any end-stage organ disease which in the opinion of the investigator may possibly affect the safety of remestemcel-l treatment - receiving an investigational cellular therapy agent

inclusion criteria - 18 years or older - patient has coronavirus disease covid-19 confirmed by real-time reverse transcription polymerase chain reaction (rt-pcr) assay or other diagnostic test - patient requiring mechanical ventilatory support with moderate to severe ards as determined by the following criteria (adapted from the berlin criteria) - bilateral opacities must be present on a chest radiograph or computed tomographic (ct) scan. these opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, or pulmonary nodules. - respiratory failure not fully explained by cardiac failure or fluid overload. - moderate to severe impairment of oxygenation must be present, as defined by the ratio of arterial oxygen tension to fraction of inspired oxygen (pao2/fio2). the severity of the hypoxemia defines the severity of the ards: - moderate ards: pao2/fio2 >100 mmhg and ≤200 mmhg, on ventilator settings that include peep ≥5 cm h2o or - severe ards: pao2/fio2 ≤100 mmhg on ventilator settings that include peep ≥5 cm h2o - high sensitivity c-reactive protein (hs-crp) serum level >4.0 mg/dl - acute physiologic and chronic health evaluation (apache iv) score >5 - the patient or his/her legally authorized representative (lar) is able to provide informed consent exclusion criteria - currently receiving extracorporeal membrane oxygenation (ecmo) or high frequency oscillatory ventilation (hfov) - females who are pregnant or lactating - patients with established positive bacterial blood cultures prior to enrollment or suspicion of superimposed bacterial pneumonia - patients with untreated hiv infection - patients who have been intubated for more than 72 hours - creatinine clearance less than 30 ml/minute - lfts (alt or ast) > 5x normal - known hypersensitivity to dmso or to porcine or bovine proteins - history of prior respiratory disease with requirement for supplemental oxygen - any end-stage organ disease which in the opinion of the investigator may possibly affect the safety of remestemcel-l treatment - receiving an investigational cellular therapy agent