PeteE, I figured you got your A and B mixed/typo'd, no big deal but wanted to be clear on HepA's fecal-oral vector...
As for SV40, yeah, that was a real Charlie Foxtrot... the contamination of oral polio vaccine didn't occur in the wild (i.e. from African monkeys to African humans), but in labs in the USA producing the vaccine virus on a substrate of homogenized monkey kidneys in the 1950's. I've seen estimates that as many as 30% of kids immunized with oral polio vaccine got SV40 virus, and this virus is associated with increased risk of developing certain kinds of cancers. Who knows what effect that has had on incidence of cancer in the US and abroad since then?
Vaccine production since then has gone from animal substrates to synthetic substrates for viral cultures, and more commonly to recombinant DNA technology that actually uses no live tissue whatsoever to maintain vaccine purity...
