The only way to insure your blood tranfusion is not contaminated is to pay to have your own blood, extracted beforehand and stores in fridges, available at hospitals, or available to be quickly transported to a hospital. This is as expensive as hell, and not really practical for most people. I would advise anyone who is told they need a blood transfusion to refuse it. If you have to lie, claim you are Jehovah's Witness or something, and it is against your religion. Your body will regenerate your own blood over time. Plasma is another issue. I don't know if the spike protein is present in plasma stored in hospitals, but I would assume that it is. I would avoid plasma transfusions as well. Of course, if you need blood to save your life, you are likely going to be so out of it, the decision will not be yours to make.