I'm going to have to reread this whole thread . . . here, I had been given to understand that, once not so long ago, polio was a dread disease which medical science and good medical practice alike were essentially powerless to stop or to cure. Then a vaccine was found, and administered widely. If there are unwanted adverse events from the vaccine, it has been said that medical science is not perfect - nothing human is - but the dread disease was conquered, except for very statistically rare instances of proof of the noted imperfection. But Russian Roulette is the comparison, eh? Better get rereading, then.....