There are many things that, as physicians, we universally take for granted. One does not need a background in medical statistics to understand that seat belts save lives and reduce injuries in car accidents. Nor do you need to have an epidemiology degree to know that tobacco smoking is causative for lung cancer. At some point in your undergraduate classes, you almost certainly heard the story of Edward Jenner, the milkmaids, and the resulting smallpox vaccine. Thanks to Dr. Jonas Salk, a true hero of the 20th Century, the last U.S. polio case was in 1979.1 The benefits of vaccination clearly outweigh the risks. Therefore measles, mumps, rubella and diphtheria should be nearly unknown today … right?