The point that I am attempting to take is that the blood and plasma industry does not and cannot know every disease and pathology in the blood of donors. Limiting your exposure to risk is a human right and medicine had better get its head on straight or they will lose a lot of money.
What are the implications of a young girl getting a blood donation from an old man? Will she age faster over her lifetime due to the old man’s stem cells colonizing her bones? Will she develop an odd interest in motor sports?
Nobody knows.
There have been some strange stories about people who have had organ transplants - I don’t know how true any of them are.
But again, the OP seems to express Covid vaccination as a main concern. I think there are concerns I’d put ahead of that.