When the local hospital warned of a brewing measles outbreak, Kaleigh Brantner urged fellow residents of this rural West Texas community to beware of vaccinating their children. Two weeks later, her unvaccinated 7-year-old son came home from school with a fever.

Many areas of the country are already dangerously below the 95 percent vaccination threshold needed to prevent measles outbreaks. The Trump administration could cause them to sink further.