The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in Wuhan, China, has become a major concern all over the world.

Convalescent plasma or immunoglobulins have been used as a last resort to improve the survival rate of patients with SARS whose condition continued to deteriorate despite treatment with pulsed methylprednisolone. Moreover, several studies showed a shorter hospital stay and lower mortality in patients treated with convalescent plasma than those who were not treated with convalescent plasma. Evidence shows that convalescent plasma from patients who have recovered from viral infections can be used effectively as a treatment of patients with active disease. To date, no specific treatment has been proven to be effective. The investigators plan to treat critical Covid-19 patients with hyperimmune plasma.

Apheresis from recovered donors will be performed with a cell separator device , with 500-600 mL of plasma obtained from each donor. Donors are males and womens , age 18 yrs or more, evaluated for transmissible diseases according to the italian law. Adjunctive tests will be for hepatitis A virus, hepatitis E virus and Parvovirus B-19. All donors will be tested for the Covid-19 neutralizing title. Each plasma bag obtained from plasmapheresis will be immediately divided in two units and frozen according to the national standards and stored separately.

Based on experience published in literature 250-300 mL of convalescent plasma will be used to treat each of the recruited patients at most 3 times over 5 days.

Inclusion Criteria:

• age >=18 yrs
• positive for reverse transcription polymerase chain reaction (RT-PCR) severe acute respiratory syndrome (SARS)-CoV-2
• Acute respiratory distress syndrome (ARDS) moderate to severe, according to Berlin definition, lasting less than10 days
• Polymerase chain reaction (PCR) positive
• signed informed consent unless unfeasible for the critical condition

Exclusion Criteria:

• proven hypersensitivity or allergic reaction to hemoderivatives or immunoglobulins
• consent denied