Putting the formatting error aside, no one is immune to any form of diseases. We are, in a way, prone to get one more than the other but to say that we are entirely protected from something is genuinely irresponsible and arrogant. They might be the one who spread diseases more than the other due to ignorance.
Well composed information. Kudos. If some people said they have HIV but would not progresses to AIDS, then that might be true because according to research, there is a defective strain of HIV which causes no symptoms and does not affect the immune system.
RE: "Blood group O can't have HIV?" Can blood group type offer immunity?