Yeah, I wouldn't recommend telling people that. There are hundreds of reasons to not be thinking straight at any particular point in time. Trying to use that as a sign is a good way to manufacture a bunch of hypochondriacs.
The virus preferentially attacks the immune system, destroying the body's defenses. The organism has more and more difficulties to defend itself, so infections appear -produced by germs, parasites or viruses- or some varieties of cancer that under normal conditions would not occur.