1. expected survival or time to withdrawal of life-sustaining treatments expected to be \<7 days. 2. do not intubate order; 3. home mechanical ventilation (noninvasive ventilation or via tracheotomy) except for continuous positive airway pressure or bi-level positive airway pressure (cpap/bipap) used solely for sleep-disordered breathing; 4. pao2/fio2 ≤75 at the time of screening. the pao2/fio2 may be estimated from pulse oximetry (appendix 1) or determined by arterial blood gas; 5. noninvasive positive pressure ventilation; 6. invasive mechanical ventilation via endotracheal intubation or tracheostomy; 7. extracorporeal membrane oxygenation (ecmo); 8. shock defined by the use of vasopressors; 9. multiple organ dysfunction or failure; 10. positive influenza a or b testing if tested as local standard of care; 11. the patient has a history of: 1. organ or hematologic transplant; 2. hiv; 3. active hepatitis b, or hepatitis c infection; 12. current treatment with: 1. chemotherapy; 2. immunosuppressive medications or immunotherapy (section 5.3 for list of prohibited immunosuppressive medications and immunotherapy) at the time of consent; 3. hemodialysis or peritoneal dialysis; 13. have a history of venous thromboembolism (vte) (deep vein thrombosis \[dvt\] or pulmonary embolism \[pe\]) within 12 weeks prior to screening or have a history of recurrent (\> 1) vte; 14. the patient is known to be pregnant or is nursing; 15. currently participating in another study of an investigational drug or therapeutic medical device at the time of consent; 16. allergy to eggs or any of the excipients in study drug.

1. expected survival or time to withdrawal of life-sustaining treatments expected to be \<7 days. 2. do not intubate order; 3. home mechanical ventilation (noninvasive ventilation or via tracheotomy) except for continuous positive airway pressure or bi-level positive airway pressure (cpap/bipap) used solely for sleep-disordered breathing; 4. pao2/fio2 ≤75 at the time of screening. the pao2/fio2 may be estimated from pulse oximetry (appendix 1) or determined by arterial blood gas; 5. noninvasive positive pressure ventilation; 6. invasive mechanical ventilation via endotracheal intubation or tracheostomy; 7. extracorporeal membrane oxygenation (ecmo); 8. shock defined by the use of vasopressors; 9. multiple organ dysfunction or failure; 10. positive influenza a or b testing if tested as local standard of care; 11. the patient has a history of: 1. organ or hematologic transplant; 2. hiv; 3. active hepatitis b, or hepatitis c infection; 12. current treatment with: 1. chemotherapy; 2. immunosuppressive medications or immunotherapy (section 5.3 for list of prohibited immunosuppressive medications and immunotherapy) at the time of consent; 3. hemodialysis or peritoneal dialysis; 13. have a history of venous thromboembolism (vte) (deep vein thrombosis \[dvt\] or pulmonary embolism \[pe\]) within 12 weeks prior to screening or have a history of recurrent (\> 1) vte; 14. the patient is known to be pregnant or is nursing; 15. currently participating in another study of an investigational drug or therapeutic medical device at the time of consent; 16. allergy to eggs or any of the excipients in study drug.

expected survival or time to withdrawal of life-sustaining treatments expected to be <7 days. do not intubate order; home mechanical ventilation (noninvasive ventilation or via tracheotomy) except for continuous positive airway pressure or bi-level positive airway pressure (cpap/bipap) used solely for sleep-disordered breathing; pao2/fio2 ≤75 at the time of screening. the pao2/fio2 may be estimated from pulse oximetry (appendix 1) or determined by arterial blood gas; noninvasive positive pressure ventilation; invasive mechanical ventilation via endotracheal intubation or tracheostomy; extracorporeal membrane oxygenation (ecmo); shock defined by the use of vasopressors; multiple organ dysfunction or failure; positive influenza a or b testing if tested as local standard of care; the patient has a history of: organ or hematologic transplant; hiv; active hepatitis b, or hepatitis c infection; current treatment with: chemotherapy; immunosuppressive medications or immunotherapy (section 5.3 for list of prohibited immunosuppressive medications and immunotherapy) at the time of consent; hemodialysis or peritoneal dialysis; have a history of venous thromboembolism (vte) (deep vein thrombosis [dvt] or pulmonary embolism [pe]) within 12 weeks prior to screening or have a history of recurrent (> 1) vte; the patient is known to be pregnant or is nursing; currently participating in another study of an investigational drug or therapeutic medical device at the time of consent; allergy to eggs or any of the excipients in study drug.

expected survival or time to withdrawal of life-sustaining treatments expected to be <7 days. do not intubate order; home mechanical ventilation (noninvasive ventilation or via tracheotomy) except for continuous positive airway pressure or bi-level positive airway pressure (cpap/bipap) used solely for sleep-disordered breathing; pao2/fio2 ≤75 at the time of screening. the pao2/fio2 may be estimated from pulse oximetry (appendix 1) or determined by arterial blood gas; noninvasive positive pressure ventilation; invasive mechanical ventilation via endotracheal intubation or tracheostomy; extracorporeal membrane oxygenation (ecmo); shock defined by the use of vasopressors; multiple organ dysfunction or failure; positive influenza a or b testing if tested as local standard of care; the patient has a history of: organ or hematologic transplant; hiv; active hepatitis b, or hepatitis c infection; current treatment with: chemotherapy; immunosuppressive medications or immunotherapy (section 5.3 for list of prohibited immunosuppressive medications and immunotherapy) at the time of consent; hemodialysis or peritoneal dialysis; have a history of venous thromboembolism (vte) (deep vein thrombosis [dvt] or pulmonary embolism [pe]) within 12 weeks prior to screening or have a history of recurrent (> 1) vte; the patient is known to be pregnant or is nursing; currently participating in another study of an investigational drug or therapeutic medical device at the time of consent; allergy to eggs or any of the excipients in study drug.

1. expected survival or time to withdrawal of life-sustaining treatments expected to be <7 days. 2. do not intubate order; 3. home mechanical ventilation (noninvasive ventilation or via tracheotomy) except for continuous positive airway pressure or bi-level positive airway pressure (cpap/bipap) used solely for sleep-disordered breathing; 4. pao2/fio2 ≤75 at the time of screening. the pao2/fio2 may be estimated from pulse oximetry (appendix 1) or determined by arterial blood gas; 5. noninvasive positive pressure ventilation; 6. invasive mechanical ventilation via endotracheal intubation or tracheostomy; 7. extracorporeal membrane oxygenation (ecmo); 8. shock defined by the use of vasopressors; 9. multiple organ dysfunction or failure; 10. positive influenza a or b testing if tested as local standard of care; 11. the patient has a history of: 1. organ or hematologic transplant; 2. hiv; 3. active hepatitis b, or hepatitis c infection; 12. current treatment with: 1. chemotherapy; 2. immunosuppressive medications or immunotherapy (section 5.3 for list of prohibited immunosuppressive medications and immunotherapy) at the time of consent; 3. hemodialysis or peritoneal dialysis; 13. have a history of venous thromboembolism (vte) (deep vein thrombosis [dvt] or pulmonary embolism [pe]) within 12 weeks prior to screening or have a history of recurrent (> 1) vte; 14. the patient is known to be pregnant or is nursing; 15. currently participating in another study of an investigational drug or therapeutic medical device at the time of consent; 16. allergy to eggs or any of the excipients in study drug.

1. expected survival or time to withdrawal of life-sustaining treatments expected to be <7 days. 2. do not intubate order; 3. home mechanical ventilation (noninvasive ventilation or via tracheotomy) except for continuous positive airway pressure or bi-level positive airway pressure (cpap/bipap) used solely for sleep-disordered breathing; 4. pao2/fio2 ≤75 at the time of screening. the pao2/fio2 may be estimated from pulse oximetry (appendix 1) or determined by arterial blood gas; 5. noninvasive positive pressure ventilation; 6. invasive mechanical ventilation via endotracheal intubation or tracheostomy; 7. extracorporeal membrane oxygenation (ecmo); 8. shock defined by the use of vasopressors; 9. multiple organ dysfunction or failure; 10. positive influenza a or b testing if tested as local standard of care; 11. the patient has a history of: 1. organ or hematologic transplant; 2. hiv; 3. active hepatitis b, or hepatitis c infection; 12. current treatment with: 1. chemotherapy; 2. immunosuppressive medications or immunotherapy (section 5.3 for list of prohibited immunosuppressive medications and immunotherapy) at the time of consent; 3. hemodialysis or peritoneal dialysis; 13. have a history of venous thromboembolism (vte) (deep vein thrombosis [dvt] or pulmonary embolism [pe]) within 12 weeks prior to screening or have a history of recurrent (> 1) vte; 14. the patient is known to be pregnant or is nursing; 15. currently participating in another study of an investigational drug or therapeutic medical device at the time of consent; 16. allergy to eggs or any of the excipients in study drug.

1. expected survival or time to withdrawal of life-sustaining treatments expected to be <7 days. 2. do not intubate order; 3. home mechanical ventilation (noninvasive ventilation or via tracheotomy) except for continuous positive airway pressure or bi-level positive airway pressure (cpap/bipap) used solely for sleep-disordered breathing; 4. pao2/fio2 ≤75 at the time of screening. the pao2/fio2 may be estimated from pulse oximetry (appendix 1) or determined by arterial blood gas; 5. noninvasive positive pressure ventilation; 6. invasive mechanical ventilation via endotracheal intubation or tracheostomy; 7. extracorporeal membrane oxygenation (ecmo); 8. shock defined by the use of vasopressors; 9. multiple organ dysfunction or failure; 10. positive influenza a or b testing if tested as local standard of care; 11. pathogens detected by a respiratory panel if tested as local standard of care; 12. the patient has a history of: 1. organ or hematologic transplant; 2. hiv; 3. active hepatitis b, or hepatitis c infection; 13. current treatment with: 1. chemotherapy; 2. immunosuppressive medications or immunotherapy (section 5.3 for list of prohibited immunosuppressive medications and immunotherapy) at the time of consent; 3. hemodialysis or peritoneal dialysis; 14. have a history of venous thromboembolism (vte) (deep vein thrombosis [dvt] or pulmonary embolism [pe]) within 12 weeks prior to screening or have a history of recurrent (> 1) vte; 15. the patient is known to be pregnant or is nursing; 16. currently participating in another study of an investigational drug or therapeutic medical device at the time of consent; 17. allergy to eggs or any of the excipients in study drug.

1. expected survival or time to withdrawal of life-sustaining treatments expected to be <7 days. 2. do not intubate order; 3. home mechanical ventilation (noninvasive ventilation or via tracheotomy) except for continuous positive airway pressure or bi-level positive airway pressure (cpap/bipap) used solely for sleep-disordered breathing; 4. pao2/fio2 ≤75 at the time of screening. the pao2/fio2 may be estimated from pulse oximetry (appendix 1) or determined by arterial blood gas; 5. noninvasive positive pressure ventilation; 6. invasive mechanical ventilation via endotracheal intubation or tracheostomy; 7. extracorporeal membrane oxygenation (ecmo); 8. shock defined by the use of vasopressors; 9. multiple organ dysfunction or failure; 10. positive influenza a or b testing if tested as local standard of care; 11. pathogens detected by a respiratory panel if tested as local standard of care; 12. the patient has a history of: 1. organ or hematologic transplant; 2. hiv; 3. active hepatitis b, or hepatitis c infection; 13. current treatment with: 1. chemotherapy; 2. immunosuppressive medications or immunotherapy (section 5.3 for list of prohibited immunosuppressive medications and immunotherapy) at the time of consent; 3. hemodialysis or peritoneal dialysis; 14. have a history of venous thromboembolism (vte) (deep vein thrombosis [dvt] or pulmonary embolism [pe]) within 12 weeks prior to screening or have a history of recurrent (> 1) vte; 15. the patient is known to be pregnant or is nursing; 16. currently participating in another study of an investigational drug or therapeutic medical device at the time of consent; 17. allergy to eggs or any of the excipients in study drug.