The primary objective is to demonstrate that, in patients with PCR-confirmed SARS-CoV-2 resulting in Acute Respiratory Distress Syndrome (ARDS), administration of 120mg/kg of body weight of intravenous Prolastin®(plasma-purified alpha-1 antitrypsin) reduces circulating plasma levels of interleukin-6 (IL-6). Secondary objectives are to determine the effects of intravenous Prolastin® on important clinical outcomes including the incidence of adverse events (AEs) and serious adverse events (SAEs).

Phase 2, randomised, double-blind, placebo-controlled, pilot trial.

The study will be conducted in Intensive Care Units in hospitals across Ireland. Patients with a laboratory-confirmed diagnosis of SARS-CoV-2-infection, moderate to severe ARDS (meeting Berlin criteria for a diagnosis of ARDS with a PaO₂/FiO₂ ratio <200 mmHg), >18 years of age and requiring invasive or non-invasive mechanical ventilation. All individuals meeting any of the following exclusion criteria at baseline or during screening will be excluded from study participation: more than 96 hours has elapsed from onset of ARDS; age < 18 years; known to be pregnant or breastfeeding; participation in a clinical trial of an investigational medicinal product (other than antibiotics or antivirals) within 30 days; major trauma in the prior 5 days; presence of any active malignancy (other than nonmelanoma skin cancer) which required treatment within the last year; WHO Class III or IV pulmonary hypertension; pulmonary embolism prior to hospital admission within past 3 months; currently receiving extracorporeal life support (ECLS); chronic kidney disease receiving dialysis; severe chronic liver disease with Child-Pugh score > 12; DNAR (Do Not Attempt Resuscitation) order in place; treatment withdrawal imminent within 24 hours; Prisoners; non-English speaking patients or those who do not adequately understand verbal or written information unless an interpreter is available; IgA deficiency.

Intervention: Either a once weekly intravenous infusion of Prolastin® at 120mg/kg of body weight for 4 weeks or a single dose of Prolastin® at 120mg/kg of body weight intravenously followed by once weekly intravenous infusion of an equal volume of 0.9% sodium chloride for a further 3 weeks. Comparator (placebo): An equal volume of 0.9% sodium chloride intravenously once per week for four weeks.

The primary effectiveness outcome measure is the change in plasma concentration of IL-6 at 7 days as measured by ELISA. Secondary outcomes include: safety and tolerability of Prolastin® in the respective groups (as defined by the number of SAEs and AEs); PaO₂/FiO₂ ratio; respiratory compliance; sequential organ failure assessment (SOFA) score; mortality; time on ventilator in days; plasma concentration of alpha-1 antitrypsin (AAT) as measured by nephelometry; plasma concentrations of interleukin-1β (IL-1β), interleukin-8 (IL-8), interleukin-10 (IL-10), soluble TNF receptor 1 (sTNFR1, a surrogate marker for TNF-α) as measured by ELISA; development of shock; acute kidney injury; need for renal replacement therapy; clinical relapse, as defined by the need for readmission to the ICU or a marked decline in PaO₂/FiO₂ or development of shock or mortality following a period of sustained clinical improvement; secondary bacterial pneumonia as defined by the combination of radiographic findings and sputum/airway secretion microscopy and culture …