Six young children at a Texas day care center have tested positive for measles — a dreaded scenario with the potential to accelerate an already out-of-control outbreak.

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.