It’s been a year since one of the worst measles outbreaks in recent U.S. history began ravaging West Texas. The highly contagious disease has continued to plague several US states, Mexico and Canada since Texas reported a epidemic among children in January 2025. The United States has been virtually free of the disease for more than a quarter century thanks to highly effective and safe vaccines, but experts now say we are on the verge of losing that status if officials determine that measles has been spreading continuously for a year.
“The United States is in the grip of its deadliest measles outbreak in decades,” says Jennifer Nuzzo, an epidemiologist and director of the Pandemic Center at Brown University. “Losing measles elimination status is official recognition that the country is on the wrong track. »
For measles, the Pan American Health Organization (PAHO) formally declares that a country has “eliminated“disease when cases can no longer be linked to each other – there is no ongoing transmission – for 12 months or more. Last November, the Americas officially lost its elimination status when PAHO’s review of epidemiological data found that Canada has not been measles-free for a year.
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“Losing measles elimination status does not result in formal sanctions, but it is an important public health signal,” the PAHO spokesperson wrote in an email to Scientific American. “Elimination is recoverable. The Americas has already experienced setbacks, including temporary loss of status in Venezuela (2018) and Brazil (2019), and has managed to regain elimination through intensified vaccination, enhanced surveillance, and rapid response to outbreaks.”
PAHO said its group that reviews the elimination status of measles in the United States and Mexico should meet again after a year of the initial outbreak in West Texas. The organization will hold its meeting on April 13 to give countries enough time to provide documentation and data, its spokesperson added. Epidemiologist Walter Orenstein, who serves on a Global Health Task Force committee that independently reviews disease elimination, expects the United States will soon follow Canada.
“It does appear that we have lost our status, but we need to look at the data,” he said, adding that the Global Health Task Force committee has not been convened at this stage to review the current situation.
The United States has maintained its measles-elimination status since stemming the spread of the virus in 2000.
“Elimination itself is a really huge public health achievement, but in the case of measles, especially because the virus is very contagious,” says Angela Rasmussen, a virologist at the University of Saskatchewan.
Measles requires very high levels of population immunity to stifle transmission; at least 95 percent of people in a community must be immune from previous infection or vaccination. And national vaccination efforts has played a central role in increasing population immunity levels in the United States, says Orenstein, a professor emeritus at Emory University who has worked to eliminate measles for decades. The two recommended doses of the measles, mumps and rubella (MMR) vaccine are 97 percent effective in preventing the disease, usually for life. “This intervention can stop and break the chains of transmission,” he says.
Before the MMR vaccine became available in 1963, the United States experienced an average of four million cases, 48,000 hospitalizations, and 400 to 500 deaths per year from measles. Most people know measles for its itchy rashbut it can cause high fevers, ear infections, severe dehydration, pneumonia and chronic inflammation of the brain or encephalitissaid Orenstein.
Such serious cases of measles, rarely seen in American hospitals for decades, have returned with a vengeance during recent outbreaks.
The first major outbreak was reported on January 20, 2025, in an under-vaccinated community in Gaines County in West Texas. From there, “cases increased exponentially,” says Katherine Wells, public health director for the city of Lubbock, Texas, located about 70 miles from Gaines County. “We saw 99 people requiring hospitalization, meaning either their oxygen levels were too low, or they developed pneumonia, or they were so dehydrated that they had to give them intravenous fluids,” Wells says. “Two young children have lost their lives to measles, and this is unprecedented. Since we have achieved measles elimination status, we have not seen any deaths.”
In 2025, the CDC recorded outbreaks in 24 states and confirmed 2,144 cases:the highest total since 1991. A large majority of infections were among children, with 69 percent among people aged 19 and under. Among these casean adult and two children died; all three were not vaccinated.
State officials declared the end of the West Texas epidemic in August 2025but outbreaks in other states continue to grow; in recent months, infections reported in South Carolina to have inflated to 434while Arizona has reported 223 casesand Utah has documented 201 cases. It remains to be seen whether these outbreaks originated from the initial epicenter in West Texas.
“If [health officials] establish that link, then there will be transmission for a full year and we will lose measles elimination status for good,” says Wells.
Previously, cases of measles appeared sporadically in people traveling to countries where the disease was more widespread, but these small outbreaks were quickly contained and never lasted more than a year. One of the main reasons measles has become so prevalent today is the decline in national vaccination rates and Growing anti-vaccine messages led by Health and Human Services Secretary Robert F. Kennedy, Jr.said Rasmussen. In response to Scientific American, A spokesperson for the Department of Health and Human Services maintained that vaccination is the most effective way to prevent measles. But the secretary had repeatedly said downplayed his security to the media During the epidemic.
“When the outbreak occurred in Texas, it took Kennedy a while to say that the vaccine was the only way to prevent measles,” says Rasmussen. “He has done everything possible to encourage alternative treatments that are its effectiveness has not been proven such as vitamin A, cod liver oil and steroids.
Wells says local public health staff and health care workers tried to mobilize quickly to provide care and vaccines to children and community members, but the Trump administration’s budget cuts, layoffs and restructuring of U.S. health agencies disrupted support for their response efforts. “Some of the federal partners that we usually have in a public health outbreak weren’t necessarily available to us,” she said.
The media have recently reported that U.S. federal officials are trying to maintain that the country is still measles-free by building a record that ongoing infections, such as those in Utah, Arizona and South Carolina, are not linked to the West Texas cases. Health officials conduct epidemiological investigations to trace infections back to common sources, as well as genomic testing to compare viruses isolated in different outbreaks. But these types of public health investigations aim to stop transmission and offer support to vulnerable groups with low vaccination rates — not to preserve a public health cachet, Nuzzo says.
“Understanding whether these cases are related is important because it can help inform efforts to control the spread of measles,” says Nuzzo, “but we should not pursue this information as if we are trying to extricate ourselves from an awkward political situation.”
Reply to I know the HHS spokesperson did not comment on the reports and wrote in a Jan. 15 email that the United States had not met the threshold required to lose phase-out status.
The resurgence of measles in the United States means cases will become commonplace and communities will likely face regular, sometimes deadly outbreaks. These outbreaks are also incredibly costly. An analysis last October The average health care cost per measles case in the United States was estimated to be $43,000, far more expensive than vaccination, Nuzzo says. She, Rasmussen and Orenstein worry that other historical vaccine-preventable diseases, such as poliocould also come back angry.
Even if there is evidence that the current outbreaks are not linked to those that began in January 2025, Wells says it may only be a matter of time before measles is no longer considered eliminated in the United States.
“We will lose this status at some point, unless we change the vaccination trajectory in our communities,” she says. “Elimination status is just a technicality. The real concern is that we are seeing transmission of measles in communities, and we have an effective way to prevent that from happening.”