US and Mexico Face Loss of Measles Elimination Status as Outbreaks Surge

A closed-door meeting this week is deciding whether the United States and Mexico have lost one of public health's clearest victories: the elimination of measles. An advisory commission of the Pan American Health Organization, known as PAHO, is going through genetic evidence from the outbreaks that have swept North America since 2024. The question it is answering is narrow. Has the same strain of measles virus been spreading continuously for a year or more? Dr. Amesh Adalja, an infectious disease physician near Pittsburgh and a senior scholar at the Johns Hopkins Center for Health Security, put it simply: the decision rests solely on genetics.

If the answer is yes, the commission will say that neither country can any longer be considered to have eliminated the disease. It will hand that finding to PAHO Director Dr. Jarbas Barbosa, a former Brazilian health official, who makes the final call. PAHO officials say an announcement is being scheduled for next week. Canada has already been through this: PAHO stripped it last year of the status it had held since 1998.

The U.S. had held its status for 30 years, having achieved elimination in 2000 after vaccination campaigns pushed childhood coverage above 97%. Health experts say 95% is the threshold needed so that an infected traveler arriving in a community does not set off an outbreak. Coverage has been slipping for years, partly because of disproven claims linking the vaccine to autism. Last year the national childhood rate fell to about 92%, and it is much lower in certain states and communities. Earlier this year, President Trump claimed without evidence that the MMR vaccine is possibly "quite lethal."

The numbers reflect that decline. Large outbreaks hit Texas, Arizona, Utah and South Carolina last year. This year's more than 5,400 confirmed cases are already double the 2025 total, driven largely by an outbreak in Pennsylvania that has dwarfed the earlier ones. Eight people have died of measles in the U.S. this year, the most in any year in more than three decades, and 2026 is the worst year for measles illness since 1991. Over the past two years, outbreaks have caused thousands of illnesses and about a dozen deaths.

Mexico's toll is heavier. It did not reach elimination status until 2016, years after the U.S. began vaccinating. Cases began surging early last year. Researchers believe the outbreak in the northern border state of Chihuahua began when an unvaccinated Mennonite child from the state traveled to Gaines County, Texas, where an outbreak was under way, and came home infected. As of this week, Mexico has reported more than 20,500 confirmed cases and 50 deaths, most of them children under 5. Measles typically starts with a high fever and a rash that begins on the face and neck. Most people recover, but it is among the leading causes of death in young children, according to the World Health Organization, and blindness and brain swelling are more common in young children and adults over 30. Early this year the WHO confirmed that Armenia, Austria, Azerbaijan, Spain, the United Kingdom and Uzbekistan had lost their status.

CDC Director Erica Schwartz said this week that losing the designation will not change how federal officials handle outbreaks. In her statement, she said vaccination, not the designation, protects Americans, and that the agency knows where transmission is occurring and is working with state and local health departments to reach those communities. Many public health experts want more: a full-throated vaccination campaign and more guidance for doctors. They fault what they describe as a politically fraught, muted federal response and blame Health Secretary Robert F. Kennedy Jr., a leading anti-vaccine voice before Trump put him in charge of the nation's health agencies. Kennedy has moved to downsize the childhood vaccination schedule, reshape a key vaccine advisory board, and praise Trump's executive order calling for spacing out the measles, mumps and rubella vaccines. Experts say that runs counter to medical groups' recommendations and would likely leave fewer children fully vaccinated.

Dr. David Margolius, director of Cleveland's health department and a leader in a coalition of big-city health departments, called the likely decision a big deal and said it represents moving backward. Next week's PAHO announcement will show whether that judgment is formalized, and whether it changes the federal approach to vaccination.