The source is the article posted in this thread. There is a distinction between donating blood and donating conv. plasma. You can donate blood for blood, cells and the such-but convalescent plasma is only taken from those with natual antibodies, no vax, for helping those very sick from covid to recover. It is different than donating blood after being vaxed. I also know this because I donated after recovering from covid so that my antibodies could be used to help recover those sickest. I also worked in an ICU and saw plasma given to those sickest to help them recover. So my comment was to clarify what conv. plasma is, and used for based on knowledge and this posts’ article. The same info can be found on NIH, FDA and general search engines defining what conv. plasma is. Hopefully I answered your question. Feel free to ask me to clarify anything else.