Across the country and around the world, children are getting sick and dying from preventable diseases—in part because some parents are choosing not to vaccinate their children. Alison Singer, President of the Autism Science Foundation, and Dr. Amy Middleman, Adolescent Medicine Specialist at the University of Oklahoma's Health Sciences Center, examine the science behind vaccinations, the return of preventable diseases, and the risks of opting out. They’re both featured in the PBS NOVA documentary “Vaccines—Calling The Shots,” which airs September 10, at 9 pm, on PBS.