CEPI (Coalition for Epidemic Preparedness Innovations) is involved in developing vaccines against SARS-CoV-2. Oslo University Hospital has received a request from CEPI if we can contribute plasma from the rehabilitation center after COVID-19. Such plasma is desirable in order to ensure the harmonization of assays used by the various vaccine developers to measure immune response after vaccination. Plasma from such patients is necessary to develop a standard to which antibody titers after vaccination can be related. Development of standard and serum panels will be carried out by the National Institute for Biological Standards and Control (NIBSC) in England, which is the WHO reference laboratory for this. Oslo University Hospital, at the Blood Bank, will arrange transport there. The plasma will be anonymized. This blood bank will employ plasmapheresis, taking a maximum sample of 600 ml (300-400 ml usually) pooled from 4-10 patients. A form for informed consent will be developed and patients will be recruited from the Department of Infectious Medicine.