Being 4/4 definitely has NOT provided me with super immunity. In fact, I sometimes wonder if it is the opposite -- more of a vulnerability gene. Although I was not a particularly sickly child, I've had far more than my share of immune system failures as an adult, including my current battle with reactivated Epstein Barr virus. I have to say, my tendency to catch colds, which used to be quite ridiculous, did get much better when I started maintaining optimal vitamin D levels. As for my relatives with at least one copy of e4 , I'd say half of them have terrific immunity, and half struggle more than they should.
4/4 but so much more