As cases increase in some places, a Yale Medicine specialist reviews the groups, including some adults, who should get vaccinated. These days, most people are vaccinated against measles, a highly contagious, life-threatening respiratory virus, when they are children. But recent reports that measles is spreading in parts of the United States are prompting some adults to wonder whether they need a measles booster shot.
As of mid-March, 301 confirmed measles cases had been reported this year across 15 jurisdictions in the U.S., from New York City to Alaska, and 93% of those cases were associated with outbreaks (defined as three or more cases), according to the Centers for Disease Control and Prevention (CDC). For comparison’s sake, the 2025 number exceeds the 285 cases the agency documented throughout 2024. In 95% of this year’s cases, people who were infected were either unvaccinated or their vaccination status was unknown. In late February, a school-age child died of the disease in West Texas, an area that has experienced an uptick in cases. In neighboring New Mexico, a second death was reported about a week later in an adult who tested positive for measles (the official cause of death in that case is awaiting confirmation). Both the child and adult were unvaccinated.
The death in Texas was the first death from measles in the U.S. since 2015. The Texas outbreak was one of three occurring in this country so far this year.