Texas authorities on Wednesday announced the first measles death in the state's outbreak of the highly contagious disease. The death, of a school-age child, is the first measles death in the U.S. since 2015,

Health officials say an unvaccinated child died at Covenant Health in Lubbock. The measles outbreak has now grown to more than 120 cases in Texas since January.

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