I've had autoimmune since the '90s so same effect as with your buddy.I had a great teacher in college who was a very established composer, but he was also diabetic. He told me that he stopped taking the flu shots that his doctor recommended because in his own words, "I end up getting the flu real bad every winter when I take one of those flu shots." That convinced me back then to stay away.
lol, is that the same guy who did this?