Eight hundred cases of measles were reported in the United States as of April 17, 2025, representing the second highest annual case count in 25 years, according to research published in the April 24 issue of the U.

Texas health officials reported 663 measles cases in the state on Tuesday, accounting for the majority of cases across the U.S., which reached nearly 900 as of Friday, according to the Centers for Disease Control and Prevention.

The outbreak would have to spread continuously for more than a year to undo the U.S.’s achievement.