Already, the U.S. has more measles cases this year than in all of 2024, the U.S. Centers for Disease Control and Prevention has said. Other states with outbreaks — defined as three or more cases — include New Mexico, Kansas, Ohio and Oklahoma. Since February, two unvaccinated people have died from measles-related causes.

The Kansas Department of Health and Environment, which reported one new measles case in the past week, now has a possible link to the Texas outbreak.

State health officials worry that declining vaccination rates have left many communities vulnerable nationwide.