The only one I have any direct experience with is polio, and that was my Dad's generation, not mine. He was one of 9 kids in his classroom (he was born in 1931, way before the Salk vaccine). There was a polio outbreak and the schools were closed. Of the 9 in his classroom (I think this was grades 4-8 in the same classroom - very rural area), 6 contracted the disease, three died, and one or two were affected so badly that they never returned to school. So I'm grateful for the polio vaccine.

As for flu shots - *shrugs* - my mother gets them every year, and I do, when I remember. When I get the shot, whatever winter sniffles I get don't last as long and don't turn into months-long infections.

But what you say has some merit. I've been looking into food research lately and am absolutely horrified. Different topic, similar horror.