vaccines didn't eradicate polio. polio is spread through the fecal oral route. people were drinking contaminated water.  3 presidents are thought to have died from drinking contaminated water at the white house.  indoor plumbing and knowing to dig your well at least 50 yards and downhill from your outhouse eradicated polio.  also, less than 1% of polio infections cause paralysis. there are other unknown factors that trigger paralysis.
United States