How Measles Is Spreading Again in the U.S.

In 2000, the United States declared measles eliminated, marking a major public health achievement made possible by widespread vaccination.

Now, that status is at risk. International health authorities are set to review whether measles has spread uninterrupted within the U.S. for at least 12 months — a technical threshold that could lead to the loss of the country’s measles-free designation.

The reassessment follows a large outbreak that began in West Texas in early 2025 and was later linked to cases across multiple states. According to the Centers for Disease Control and Prevention, more than 2,200 measles cases were reported nationwide last year, the highest number in decades.

Measles is one of the most contagious viruses known, infecting up to nine out of ten unvaccinated people who are exposed. Stopping its spread requires community vaccination rates of about 95%, but national coverage has slipped below that level, with some communities far lower.

Public health officials point to vaccine hesitancy, misinformation, and uneven access to care as key drivers.

Doctors stress that the real concern isn’t the loss of a label, but the conditions that allow measles to spread again — especially in schools, childcare centers, and other shared spaces.