Nope.
The general idea is that your immune function, “Health”, slowly normalizes to 0. Eating healthy stuff like fruit, vegetables, etc can raise it; Junk Food can lower it, as can mutagenic stuff. Vitamins and flu-shots exist to boost your health stat; flu shot lasts for about a season or two, and vitamins are generally good at one per day (if you’ve not had a flu shot).
If you’ve specifically been doing unhealthy things like drinking a gallon of mutagen at one go, then you may want more than one vitamin afterward.
The Leukocyte Breeder pumps bionic power into directly increasing Health, so it’s good to have and give a shot every so often, just in case.
Some folks avoid the issue altogether by wearing a filter or gas mask constantly. Since you get sick through your mouth, environmental protection on your mouth can reduce or eliminate colds and flu. (So the air-filter aug kinda helps too.)