Diseases that were largely eradicated 40 years ago are returning. Across the world, children are getting sick and dying from preventable conditions because nervous parents are skipping their children's shots. How do parents decide whether to vaccinate or not, and what are the risks to the child and to society? Featuring research scientists, pediatricians, psychologists, anthropologists, and parents, this program travels the globe to look at the science behind vaccinations, track epidemics, and investigate the serious human costs of opting out.