My cousin who is 43 and had a kidney/pancreas transplant is at the hospital for dialysis every other day (antibiotics fried his transplanted kidney a year after he received it. ). He received his first Pfizer shot and was extremely ill. He described it as a very bad case of the flu with diarrhea and vomiting that lasted 2-3 days. He saw his doctor about it who told him that the first shot gave him 83% protection. He said he doctor also warned him that the efficacy of the shot was only expected to last 6 months after which time he’ll have to get a booster. So my cousin opted not to get his second shot.