The FDA won't allow convalescent plasma collection from vaccinated people (https://www.fda.gov/regulatory-information/search-fda-guidance-documents/investigatio

The FDA won't allow convalescent plasma collection from vaccinated people (https://www.fda.gov/regulatory-information/search-fda-guidance-documents/investigational-covid-19-convalescent-plasma https://www.fda.gov/regulatory-information/search-fda-guidan...), on the grounds that their antibody response might be different than the response from a natural infection. (I don't know enough to judge whether or not this could be expected to cause practical issues.)