An unvaccinated school-aged child has died in the measles outbreak in Texas, which has seen 124 reported cases of the disease. It's the first measles death in the U.S. since 2015. Pediatrician and infectious disease specialist Dr. Adam Ratner, author of Booster Shots: The Urgent Lessons of Measles and the Uncertain Future of Children's Health, says the outbreak is part of a 'disturbing' trend.