One hundred patients hospitalized and in need of oxygen treatment due to Covid-19 should be randomized and 50% treated with 200 ml convalescent plasma x 3 and 50% given ordinary treatment.

Primary outcome is number of days the patients need oxygen within 28 days from inclusion.

Secondary outcome is number of days in hospital, number of days in respirator and mortality.

Side effects of treatment is monitored.

Subjects with previous verified COVID-19 are asked to donate plasma 14 days or later after recovery. IgG antibodies against Covid-19 are measured and only subjects with high titers are accepted. Plasmaphereses is done and up to 600 ml plasma is drawn and aliquoted in 200 ml portions.

Patients with acute respiratory symptoms, verified Covid-19, hospitalized and in need of oxygen treatment are asked to participate in the study. The patients are randomized 50/50 to get either convalescent plasma or routine treatment without plasma. The patients randomized to get plasma will have infusion of 200 ml blood group compatible convalescent plasma daily during three days from different donors.

The clinical course will be carefully monitored and days with oxygen requirement will be compared between the groups. Secondary clinical outcomes as mortality, need of assisted ventilation, total days in hospital and side effects to treatment will be observed.

Inclusion Criteria:

• Verified diagnosis of Covid-19
• <94% oxygen saturation
• willingness to participate
• ability to sign informed consent

Exclusion Criteria:

• unability to understand information and sign informed consent
• immunosuppressed patient