would be interesting to see how really dark black people with high natural sun insulation are fairing. I mean its armchair biology but you could theorize that people with very dark black skin that work in office and dont see much sunlight would be more susceptible to the coldflu seasons...

I dont remember seeing anything like that, and one of my workmates from Kenya, who has been told that her Vit D levels are too low in winter (by her GP) and that she should go for walks at lunchtime to get them up a bit, doesn't seem to get especially hammered by the cold/flu season.

That is a anecdotal data pool of (1) though :-P