Convalescent plasma from Norwegian blood donors to treat COVID-19.

Background: At the start of the pandemic, the Norwegian Directorate of Health and Norwegian blood banks initiated the production of COVID-19 convalescent plasma within the framework of clinical studies. In this article we describe the blood donors who participated.

Material And Method: Blood donors who had recovered from COVID-19 were recruited to donate single donor plasma for the purpose of patient treatment. Data on the course of infection, leukocyte antibodies and antibody level against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) per plasma unit were registered after informed consent was obtained. We calculated a disease score defined as the total number of self-reported symptoms/findings and hospitalisation where relevant (score 0-⁠11).

Results: A total of 1644 plasma units were collected from 266 plasma donors at 12 blood banks. Median disease score was 5 (interquartile range 3-⁠6), and 15 donors had recovered from pneumonia and/or been hospitalised. A total of 599/1644 plasma units from 106/266 donors met our requirement for SARS-CoV-2 antibody content (> 60 % inhibition of virus binding to angiotensin-converting enzyme 2 (ACE2)) or positive virus neutralisation test. The antibody level in donors waned over time following infection, and showed no clear correlation with disease score.

Interpretation: The number of symptoms and findings in blood donors could not predict antibody response at individual level, and antibody testing was crucial for the production of effective convalescent plasma.