He's been told that before, and he ignores it because it doesn't justify his selfishness. I put him on ignore, and so should everyone else.1) Diabetes and heart disease aren't transmissable diseases whereby your illness kills others. Well, discounting having a heart attack whilst you're driving a car, but that doesn't really count.
2) A vaccine is a few minutes of your time, plus a few side effects for a couple of days. Sorting out diabetes and heart disease are widespread if not wholesale lifestyle change over the course of months-years-lifetime. The two do not even remotely compare in terms of invasiveness into people lives.