US to Lose Measle-Free Status in January

As of Dec. 16, a total of 1,958 confirmed measles cases were reported in the U.S., according to the Centers for Disease Control and Prevention (CDC). (The CDC numbers do not include probable measles cases reported by jurisdictions that have not been confirmed yet.) Among these, 1,934 measles cases were reported by 43 states, and 24 cases were reported among international visitors to the U.S.

As measles-mumps-rubella (MMR) vaccination rates dwindle, the U.S. is experiencing the highest number of cases in more than 30 years. The CDC confirmed 49 outbreaks in 2025, and 88% of confirmed cases (1,713 of 1,958) are outbreak-associated. For comparison, 16 outbreaks were reported during 2024 and 69% of cases (198 of 285) were outbreak-associated.

Currently, the largest U.S. outbreak is in South Carolina. As of Dec. 16, the South Carolina Department of Public Health has reported 138 cases of measles since July 9, most centered in Upstate South Carolina, which includes Greenville and Spartanburg.

Another of the largest measles outbreaks in the U.S. has been confirmed in the bordering areas between Utah and Arizona. According to state health departments as of Dec. 16, 125 cases have been confirmed in Utah  while 190 cases have been confirmed in Arizona.

Earlier this year, CMM reported the end of this year’s largest measles outbreak centered in West Texas. As of Dec. 16, the CDC has confirmed 803 cases of measles in Texas since January—the most of any state this year. 

In September, the Advisory Committee on Immunization Practices (ACIP) voted to change national guidelines on the measles-mumps-rubella (MMR) vaccine.

In November, the Americas arm of the World Health Organization (WHO) said the continued measles spread in Canada, Mexico, and the U.S. caused the countries to lose their measles-free status. The Americas was the first region in the world to eliminate measles twice. However, as of October, endemic transmission of measles has been reestablished in Canada, where the virus has circulated for at least 12 months. The U.S. is set to lose its measles-free status in January.

As of Nov. 7, 12,596 confirmed measles cases have been reported across ten countries (approximately 95% of the region’s cases in Canada, Mexico, and U.S.), a 30-fold increase compared to 2024. Twenty-eight deaths have been recorded: 23 in Mexico, three in the U.S., and two in Canada. Active outbreaks are ongoing in the U.S., Canada, Mexico, Bolivia, Brazil, Paraguay, and Belize.

“This loss represents a setback—but it is also reversible,” said Dr. Jarbas Barbosa, Pan American Health Organization director, “Until measles is eliminated worldwide, our region will continue to face the risk of reintroduction and spread of the virus among unvaccinated or under-vaccinated populations. However, as we have demonstrated before, with political commitment, regional cooperation, and sustained vaccination, the region can once again interrupt transmission and reclaim this collective achievement.”