Vaccine hesitancy has been rising for years in the United States. Doctors and parents in one rural county are confronting the consequences.

The first measles death in the growing outbreak in West Texas was a school-aged child. The child was unvaccinated and had been hospitalized in Lubbock, Texas, said Lauren Adams, Lubbock city spokesperson. This is the first US measles death since 2015, when a woman in Washington state died.

Here’s what to know about the outbreak after the first U.S. death since 2015 from the highly contagious—but preventable—respiratory disease.