- Severity of symptoms at enrollment: 1) Less severe hospitalized subjects are those who (but not limited to): are hemodynamically stable; may require oxygenation with facemask, facetent, nasal canula, etc; may or may not have radiological signs of lower respiratory tract disease; or have exacerbation of underlying chronic disease, including asthma, chronic obstructive pulmonary disease (COPD), or other cardiovascular conditions not leading to hemodynamic compromise. 2) Critically ill hospitalized subjects are those who (but not limited to): require CPAP, BIPAP, mechanical ventilation; have hemodynamic instability (with or without pressor support); or have central nervous system involvement (example encephalopathy, encephalitis).