Ok thanx, I looked it up and apparently the red cross has recently to some extent restarted their convalescent plasma program: https://www.redcross.org/about-us/news-and-events/press-release/2022/red-cross-helps-support-immunocompromised-covid-19-patients.html It's hard to tell the exact issue but it could be that they test for spike protein antibodies to tell antibody levels and the vaccine always makes that number high. However natural immunity would yield antibodies to the whole virus, not just the spike which is a more robust immune response. I would not be surprised if they know the best immunity is natural and it's more a matter of it being easier to test and verify for those that do not have the vax. But then again who knows for sure, there could be more than one reason why they have made those choices. ;-P