1. evidence of critical covid-19 2. inability to utilize nebulized drugs, or history of bronchospasm with inhaled medications 3. age \<12 years; 4. mean arterial pressure \< 65 mm hg after initial hospital stabilization, 5. non-covid-19 irreversible underlying condition with projected fatal course within 6 months or with high risk of mortality; 6. immunosuppressive treatment for transplant or other diseases associated with high mortality; 7. stage iv cancer or cancer on active treatment with chemotherapy immunotherapy or checkpoint inhibitors; acute renal failure or chronic renal insufficiency with gfr less than 30; chf new york heart association class iii or iv, new neurologic disorder in the last 3 months or chronic neurologic disorder or other that would impact on assessing the resolution of severe covid-19 respiratory failure 8. myocardial infarction in previous six months or troponin \>0.5 9. recent history of venous thrombotic events (pe / dvt) within the last 3 months. 10. new diagnosis of atrial fibrillation within the last 3 months. acceptable if greater than 3 months and well controlled in the opinion of the investigator 11. watery diarrhea requiring replacement of 1 liter or more of iv fluids and electrolytes 12. pregnancy

1. evidence of critical covid-19 2. inability to utilize nebulized drugs, or history of bronchospasm with inhaled medications 3. age \<12 years; 4. mean arterial pressure \< 65 mm hg after initial hospital stabilization, 5. non-covid-19 irreversible underlying condition with projected fatal course within 6 months or with high risk of mortality; 6. immunosuppressive treatment for transplant or other diseases associated with high mortality; 7. stage iv cancer or cancer on active treatment with chemotherapy immunotherapy or checkpoint inhibitors; acute renal failure or chronic renal insufficiency with gfr less than 30; chf new york heart association class iii or iv, new neurologic disorder in the last 3 months or chronic neurologic disorder or other that would impact on assessing the resolution of severe covid-19 respiratory failure 8. myocardial infarction in previous six months or troponin \>0.5 9. recent history of venous thrombotic events (pe / dvt) within the last 3 months. 10. new diagnosis of atrial fibrillation within the last 3 months. acceptable if greater than 3 months and well controlled in the opinion of the investigator 11. watery diarrhea requiring replacement of 1 liter or more of iv fluids and electrolytes 12. pregnancy

evidence of critical covid-19 inability to utilize nebulized drugs, or history of bronchospasm with inhaled medications age <12 years; mean arterial pressure < 65 mm hg after initial hospital stabilization, non-covid-19 irreversible underlying condition with projected fatal course within 6 months or with high risk of mortality; immunosuppressive treatment for transplant or other diseases associated with high mortality; stage iv cancer or cancer on active treatment with chemotherapy immunotherapy or checkpoint inhibitors; acute renal failure or chronic renal insufficiency with gfr less than 30; chf new york heart association class iii or iv, new neurologic disorder in the last 3 months or chronic neurologic disorder or other that would impact on assessing the resolution of severe covid-19 respiratory failure myocardial infarction in previous six months or troponin >0.5 recent history of venous thrombotic events (pe / dvt) within the last 3 months. new diagnosis of atrial fibrillation within the last 3 months. acceptable if greater than 3 months and well controlled in the opinion of the investigator watery diarrhea requiring replacement of 1 liter or more of iv fluids and electrolytes pregnancy

evidence of critical covid-19 inability to utilize nebulized drugs, or history of bronchospasm with inhaled medications age <12 years; mean arterial pressure < 65 mm hg after initial hospital stabilization, non-covid-19 irreversible underlying condition with projected fatal course within 6 months or with high risk of mortality; immunosuppressive treatment for transplant or other diseases associated with high mortality; stage iv cancer or cancer on active treatment with chemotherapy immunotherapy or checkpoint inhibitors; acute renal failure or chronic renal insufficiency with gfr less than 30; chf new york heart association class iii or iv, new neurologic disorder in the last 3 months or chronic neurologic disorder or other that would impact on assessing the resolution of severe covid-19 respiratory failure myocardial infarction in previous six months or troponin >0.5 recent history of venous thrombotic events (pe / dvt) within the last 3 months. new diagnosis of atrial fibrillation within the last 3 months. acceptable if greater than 3 months and well controlled in the opinion of the investigator watery diarrhea requiring replacement of 1 liter or more of iv fluids and electrolytes pregnancy