Ive had chicken pox 3 or 4 times when younger and even got shingles between 16 and 18. I don't recall exact date. Luckily my shingles wasn't painful beyond the itchy pox things going up my arm.

I'm one of rare people that never developed immunity or resistance.

And when I was in the military, due to this they didn't give me smallpox vaccine, I think, anyway, my memory is foggy. But I specifically remember the events occurred, just not the timing exactly.