Across the Americas, a quiet deliberation is underway in which genetic evidence, rather than headlines, will decide whether the United States and Mexico still hold a hard-won victory over measles. Long after vaccines first pushed the disease to the edge of memory, the question is whether a virus has now been allowed to circulate long enough within these borders to count as native again. The answer carries weight beyond statistics: it marks the moment a community's collective protection, built on childhood immunization and trust, begins to fray. A decision expected next week will name a loss th
US and Mexico Face Loss of Measles Elimination Status as PAHO Experts Convene
At least 50 measles-related deaths in Mexico, most among children under 5, and eight measles-associated deaths in the US this year.
The virus is now spreading within the nations' borders.
Mark
Why does a designation matter if the virus is already spreading?
Mimi
It's a formal marker that the spread is now sustained. Experts expect the finding to say measles has returned to the U.S. and Mexico, and Dr. Margolius called that moving backward.
Luke
But the decision isn't made yet. The commission is reviewing the genetics, and Director Barbosa has the final say. What's solid is the expectation, not the ruling.
Mark
What's the test?
Mimi
Whether the same virus has circulated for a year or more. Dr. Adalja said it's solely genetics.
Luke
Worth noting that's his description of the process. The meeting is closed, so we can't see the data.
Mark
Mexico's numbers are much bigger than the U.S.
Mimi
More than 20,500 cases and 50 deaths, mostly children under 5, against over 5,400 cases and eight deaths here.
Luke
Those are reported confirmed counts. The Chihuahua link to Texas is researchers' belief, not a proven chain.
Mark
And the CDC's stance?
Mimi
Director Schwartz says vaccination protects people, not the label. Critics want a louder campaign and blame Kennedy.
Luke
That's criticism from experts. What's documented is Kennedy's moves on the schedule and advisory board; the claim that they'd lower vaccination is the experts' projection.
El Pulso
- A panel of international experts is parsing genetic data to determine whether one measles strain has circulated unbroken for more than a year across North America.
- The US has logged over 5,400 cases and eight deaths this year, double all of 2025, with a Pennsylvania outbreak leading the surge.
- Mexico's toll has climbed past 20,500 cases and 50 deaths, most among children under five, after an outbreak that began with a single traveler.
- Vaccination rates have slipped below the roughly 95% threshold needed for protection, and federal moves to shrink schedules have alarmed public health leaders.
- PAHO Director Jarbas Barbosa holds the final say, with an announcement expected next week, while the CDC insists its outbreak response will not change.
Across the Americas, a quiet deliberation is underway in which genetic evidence, rather than headlines, will decide whether the United States and Mexico still hold a hard-won victory over measles. Long after vaccines first pushed the disease to the edge of memory, the question is whether a virus has now been allowed to circulate long enough within these borders to count as native again. The answer carries weight beyond statistics: it marks the moment a community's collective protection, built on childhood immunization and trust, begins to fray. A decision expected next week will name a loss that many experts believe was years in the making.
This week, a commission of the Pan American Health Organization is reviewing genetic evidence to decide whether the United States and Mexico have lost their measles elimination status. Experts widely expect the answer to be yes. The test is purely genetic: if the same strain has spread continuously for a year or more since 2024, the countries can no longer be considered measles-free. The finding goes to PAHO Director Jarbas Barbosa, who will make the final call, with an announcement expected next week.
The United States earned its status in 2000, after childhood vaccination rose above 97%. That protection has eroded. Coverage fell to about 92% last year, well below the roughly 95% needed to stop an outbreak when an infected traveler arrives, and disproven claims linking vaccines to autism have contributed. This year's more than 5,400 confirmed cases already double 2025's total, driven largely by a Pennsylvania outbreak. Eight deaths make this the deadliest year in over three decades.
Mexico's toll is heavier. Its outbreak in Chihuahua is traced to an unvaccinated child who returned from Texas, and more than 20,500 cases and 50 deaths have followed, most among children under five.
CDC Director Erica Schwartz says the designation will not change federal outbreak response, and that vaccination itself protects Americans. Many public health leaders disagree. They call for a stronger vaccination campaign and clearer guidance for doctors, criticizing a muted federal response and the moves by Health Secretary Robert F. Kennedy Jr. to shrink the childhood schedule. Cleveland's health director, David Margolius, called the expected decision a big deal and a step backward.
This week, behind closed doors, an advisory commission of the Pan American Health Organization is going through genetic data on measles. The question before it is whether the United States and Mexico have lost one of their major public health achievements: the elimination of the disease. Experts expect the answer to be yes.
The commission is looking at whether the same strain of virus has circulated continuously for a year or more in the outbreaks that have moved through North America since 2024. Dr. Amesh Adalja, an infectious disease physician near Pittsburgh and a senior scholar at the Johns Hopkins Center for Health Security, described the standard simply: it is based solely on genetics. If the answer is yes, the commission will say the countries can no longer be considered measles-free, because the virus is spreading within their borders. The commission passes its 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. Last year the organization took Canada's elimination status, held since 1998.
The U.S. had held its status since 2000, after vaccination campaigns pushed childhood coverage above 97%. Experts say about 95% is needed so that when an infected traveler arrives, enough people are protected to keep an outbreak from starting. Rates have slipped for years, partly because of disproven claims linking the vaccine to autism. Last year the national childhood rate fell to about 92%, and it was far lower in some states and communities. Earlier this year, President Donald 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 a Pennsylvania outbreak that has dwarfed the earlier ones. Eight measles-associated deaths this year are the most in any year in over 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 in the U.S.
Mexico's toll is heavier. It did not reach elimination status until 2016. Cases began surging early last year, and researchers think the outbreak in the northern state of Chihuahua traced back to an unvaccinated Mennonite child who traveled to Gaines County, Texas, where an outbreak was underway, and returned infected. As of this week, Mexico has reported more than 20,500 confirmed cases and 50 measles-related deaths, most of them children under 5. The problem extends beyond North America: early this year the World Health Organization 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 a statement she said vaccination, not the designation, protects Americans, and that the agency knows where transmission is happening and is working with state and local health departments to reach those communities.
Many public health experts want more. They say the moment calls for a vigorous campaign promoting vaccination and more guidance for doctors, and they fault what they call a politically fraught, muted federal response. They 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 shrink 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. Dr. David Margolius, Cleveland's health director and a leader in a coalition of big-city health departments, called the expected decision a big deal and a step backward.
The verdict should come next week, from Barbosa.
Citas Notables
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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