Which vaccine has had the greatest impact?

Lantern Slide, The College of Physicians of Philadelphia We hosted a contest for Facebook fans of the Mütter Museum/The College of Physicians of Philadelphia. This is their chance to win fabulous prizes from the Mütter Museum store.

The rules: submit a comment to this blog post that describes which vaccine you think has had the greatest impact on human health and explains why. The comment had to comply with our blog comments/moderation policy (see below).

We chose THREE winners from those of you who posted a comment. Congratulations to knittingclio, Jaime, and Melissa! We hope you like your gifts!