Convalescent Plasma Donor Vaccine Study An Observational Antibody Level Study.

This is an observational study to determine changes in antibody levels in individuals who have previously donated COVID-19 convalescent plasma (CCP) and have now received at least one dose of a COVID-19 vaccine. At present these donors could no longer donate CCP as their virus-neutralising antibody levels do not reach the level required (Euroimmun of at least 6 IgG signal/control cutoff). Two blood samples (9 ml total) will be collected at a local NHSBT donor centre to test the levels of the virus-neutralising antibodies in the plasma against different viral strains. The results of this study will: 1. Determine whether NHSBT will collect CCP or plasma for medicines (PFM) from vaccinated members of the public that could have boosted antibody levels following vaccine administration. 2. Understand if antibody levels rebound to a concentration suitable for CCP and PFM. 3. Provide the evidence to support the use of CCP for the early treatment in COVID (currently under consideration as a collaboration with European partners). 4. Assist in development of recording vaccination status on NHSBT databases of donors.