Can you tell me why an individual with a compromised immune system (for example, a person with aids) may be unable to?

Suppressed immunity: THere are many reasons for a compromised immune system. This can cause increased susceptibility to infections of various kinds. As such, one must take extra care to avoid things that will increase infection risks, such as direct contact with someone who is ill. As well, some live vaccines may be contraindicated, and certain types of travel may be ill-advised.