This is a very interesting topic OP. Since acquiring my condition 8 years ago (which is suspect is immune related) I have not been sick. Previous to that I would get sick what I would consider a normal amount. I've been recently wondering if it has to do with being mostly housebound and getting plenty of rest or if it has to do with an overactive immune system. Still, 8 years is a freaking long time to go without getting a cold imo.