>So, to be clear, the first generation of polio vaccines did _not_ give polio to those who took them. The second generation, which has historically been more po

>So, to be clear, the first generation of polio vaccines did _not_ give polio to those who took them. The second generation, which has historically been more popular because people are more comfortable with oral than injected vaccines, occasionally does, though it's extremely rare. My recollection of the details was mistaken. Thanks for the correction.