In 2000, the United States declared that measles had been eliminated. But just 15 years later, the disease made a comeback—and it hasn’t gone away since. In this episode, Dr. Adam Ratner, director of the Division of Pediatric Infectious Diseases at NYU and author of Booster Shots: The Urgent Lessons of Measles and the Uncertain Future of Children's Health, explains why measles outbreaks are occurring again—as vaccine hesitancy and the antivax movement is on the rise—and what this means for the future of children’s health.

Ratner describes why measles is the most contagious disease we know of, and why it can be particularly harmful to children. As vaccination rates for children and adults continue to decrease in the U.S., are we at risk of undoing decades of medical progress? And what can we do to stop it?