In a closed-door session this week, advisers to the Pan American Health Organization are weighing a question that carries decades of collective effort on its shoulders: whether the same measles strain has moved quietly through the United States and Mexico for a year or more since outbreaks began in 2024. A yes would strip both nations of an elimination status hard won at the turn of the millennium, a reminder that protection against an old disease is never permanent but must be renewed in every generation of children. The decision now rests with PAHO's director, and its announcement is expecte
US and Mexico Face Loss of Measles Elimination Status as PAHO Experts Weigh Genetic Evidence
Measles has caused about a dozen deaths in the US in two years and at least 50 deaths in Mexico, mostly children under 5, with over 20,500 confirmed cases there.
Eight deaths this year, the most in more than three decades
Mark
What exactly is the commission deciding?
Mimi
Whether the same measles virus has kept spreading for a year or more in the outbreaks since 2024. If it has, elimination is lost.
Mark
And that's purely scientific?
Mimi
Dr. Adalja says it's solely based on genetics. But the final call belongs to PAHO's director, Dr. Jarbas Barbosa.
Luke
Worth noting the outcome isn't announced yet. Experts expect loss of status, but that's an expectation, not a finding.
Mark
The CDC says the designation doesn't matter much. Is that fair?
Mimi
Director Erica Schwartz says vaccination is what protects people, and the agency is working with local health departments. Critics say the federal message is muted and call for a bigger campaign.
Luke
That criticism is attributed to unnamed many experts, and the blame on Kennedy is their view. The source confirms his policy moves, not that they caused the outbreaks.
Mark
What's the vaccination picture?
Mimi
About 92% nationally last year, below the 95% experts say is needed, and much lower in some places.
Luke
Also, the Chihuahua origin is what researchers think, not something proven. And the source doesn't say how many of the 5,400 cases are in Pennsylvania.
Mimi
Fair. What is firm is the count: 5,400 US cases, 20,500 in Mexico, and 50 Mexican deaths, mostly small children.
Le Pouls
- A closed-door PAHO commission is reviewing genetic data to determine whether one measles strain has circulated continuously in the US and Mexico for over a year.
- If confirmed, both countries lose the elimination status they earned in 2000 and 2016, a loss that already befell Canada last year.
- US childhood vaccination has slipped to about 92%, below the 95% threshold needed to keep an infected traveler from sparking outbreaks.
- With more than 5,400 US cases this year and over 20,500 in Mexico, the toll is climbing, and children under five are dying.
- The CDC says the designation changes nothing about its approach, while public health leaders call for a louder, more urgent vaccination push.
- PAHO's director will announce the final ruling next week, and the outcome will show whether North America joins the growing list of lost-status nations.
In a closed-door session this week, advisers to the Pan American Health Organization are weighing a question that carries decades of collective effort on its shoulders: whether the same measles strain has moved quietly through the United States and Mexico for a year or more since outbreaks began in 2024. A yes would strip both nations of an elimination status hard won at the turn of the millennium, a reminder that protection against an old disease is never permanent but must be renewed in every generation of children. The decision now rests with PAHO's director, and its announcement is expected within days, marking a moment when a community's shared immunity is measured not in promises but in the quiet arithmetic of who is still vaccinated.
A closed-door meeting is underway this week in which a commission of advisers to the Pan American Health Organization is reviewing genetic data on measles. The central question is narrow but weighty: has the same strain of the virus been circulating in the United States and Mexico for a year or more? If it has, both countries will lose the measles elimination status they once won, a status that Canada already lost last year.
The outbreaks began in 2024 and have spread across North America since. Experts expect the genetic findings to confirm that measles is again moving continuously within both countries. PAHO Director Dr. Jarbas Barbosa will make the final call, with an announcement expected next week.
For the United States, the stakes are three decades of progress. Elimination was achieved in 2000, when childhood vaccination coverage topped 97%. Today coverage has fallen to about 92% nationally, below the roughly 95% needed to keep an infected traveler from sparking a larger outbreak. This year's more than 5,400 confirmed cases are double the 2025 total, and eight deaths make it the deadliest year in over three decades. Public health leaders in big cities call the likely decision a step backward.
CDC Director Erica Schwartz has said the loss of the designation will not change federal handling of outbreaks, insisting that vaccination, not a title, is what protects people. Many experts want a far more forceful response, and they criticize federal leadership for a muted approach and for moves to scale back the childhood vaccine schedule.
Mexico's toll is heavier. More than 20,500 cases have been confirmed and at least 50 people have died, most of them children under five. Researchers trace the outbreak in Chihuahua to an unvaccinated child who traveled to Texas and came home infected.
The question reaches beyond North America. Several countries have already lost their status this year. Next week's announcement will show whether the United States and Mexico join them.
A closed-door meeting is under way this week in which a commission of advisers to the Pan American Health Organization is going through genetic data on measles. The question before them is narrow but heavy: has the same strain of the virus been circulating in the United States and Mexico for a year or more? If so, both countries will be judged to have lost the measles elimination status they once won.
The outbreaks in question began in 2024 and have torn through North America since. Dr. Amesh Adalja, an infectious disease physician near Pittsburgh and a senior scholar at the Johns Hopkins Center for Health Security, described the standard plainly: it is solely based on genetics. Experts expect the finding to confirm that measles is again spreading continually within both countries' borders. The commission will pass its determination 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 of the status it had held since 1998 last year.
For the United States, the stakes are three decades of progress. Elimination was achieved in 2000, after vaccination campaigns pushed childhood coverage above 97%. Health experts say 95% is the level needed so that an infected traveler arriving in a community meets so many vaccinated people that no outbreak takes hold. Dr. David Margolius, who directs Cleveland's health department and helps lead a coalition of big-city health departments, called the likely decision a big deal and said it represents moving backward.
The numbers explain why. Childhood vaccination fell to about 92% nationally last year, and is far lower in some states and communities. The decline has built for years, in part because of disproven claims linking the vaccine to autism. Earlier this year Trump claimed, without evidence, that the MMR vaccine is possibly quite lethal. Last year measles exploded in Texas, Arizona, Utah and South Carolina. This year's more than 5,400 confirmed cases are already double the 2025 total, driven largely by a Pennsylvania outbreak that has dwarfed the earlier ones. Eight measles-associated deaths this year are the most in any year in more than three decades, and it is the worst year for measles illness since 1991. Over two years, about a dozen people have died.
CDC Director Erica Schwartz said this week that losing the designation will not change how federal officials handle outbreaks. In her statement she said the designation is not what protects Americans, vaccination does, 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 stepped-up, full-throated push for vaccination and more guidance for doctors. They fault what they call 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 vaccine. Experts say that runs counter to medical groups' recommendations and would likely leave fewer children fully vaccinated.
Mexico's toll is heavier. It did not achieve elimination until 2016, and its vaccine arrived years after the first U.S. licensure in 1963. Cases surged early last year. Researchers believe the outbreak in the northern border state of Chihuahua began when an unvaccinated Mennonite child from there traveled to Gaines County, Texas, where an outbreak was under way, and returned infected. As of this week, more than 20,500 cases are confirmed nationwide and 50 people have died, most of them children younger than 5.
The problem extends beyond North America. Earlier this year the World Health Organization confirmed that Armenia, Austria, Azerbaijan, Spain, the United Kingdom and Uzbekistan had lost their status. Next week's PAHO announcement will show whether the United States and Mexico join that list.
Citations marquantes
The measles elimination designation is not what protects Americans. Vaccination does.— CDC Director Erica Schwartz
It's a big deal. The decision represents us moving backward.— Dr. David Margolius, Cleveland health department director
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