A Study of APL-9 in Adults With Mild to Moderate ARDS Due to COVID-19

Inclusion Criteria: * Be at least 18 years of age at time of informed consent * Diagnosis of active SARS CoV 2 infection using viral RNA or viral antigen within 7 days of screening * Respiratory failure requiring oxygen supplementation or either invasive or noninvasive mechanical ventilation with PaO2/FiO2 ratio \>100 mm Hg. Respiratory failure cannot be fully explained by cardiac failure or fluid overload. Exclusion Criteria: * Treatment with immune checkpoint inhibitors, or other immunomodulators within 3 months prior to study enrollment (however, treatment with convalescent plasma, steroids, IL-6 inhibitors, and antiviral agents is NOT excluded) * Active bacterial, fungal, or parasitic infection * History of neuromuscular degenerative disease (eg, amyotrophic lateral sclerosis, Duchenne muscular dystrophy, or multiple sclerosis) * Current participation in an interventional clincial trial * Subjects who have, at screening, been on mechanical ventilation for \>7 days Have evidence of kidney and liver failure at screening * Have a hereditary complement deficiency * Pregnancy or breastfeeding