measles is making a comeback in the Americas.
The United States may soon have to return its gold medal status of measles elimination, a ranking bestowed by the World Health Association that signals the virus is under control and not widely circulating. The status loss would follow a similar loss from the United States’ neighbour to the north, Canada, a reminder that officials have a tenuous grip on a highly contagious virus.
Countries are considered measles-free if the virus has not continually spread among residents for at least 12 months. People who catch the virus somewhere else and arrive infected are considered imported cases.
“Getting to the point of elimination is like getting a gold medal,” says William Schaffner, an infectious diseases physician at Vanderbilt University in Nashville. “It’s also an exmaple to other countries, so that they know it’s possible.”
In 2016, the Americas as a whole became the only WHO region to have eliminated measles from all countries. But an outbreak in Venezuela stripped the region of its status in 2018, and spread to Brazil the following year. Venezuela regained elimination status in 2023 but Brazil,and the region, reclaimed the title in November 2024.
A measles outbreak in Canada began in October 2024. Continuous transmission more than a year later signifies that the virus is no longer eliminated, the Public Health Agency of Canada announced November 10.
Now, the United States has until January 20, 2026 — one year after an outbreak began in West Texas — to bring measles cases under control without losing its elimination status. In 2025, the U.S. Centers for Disease Control and Prevention has documented 1,753 measles cases and three deaths across 42 states. More than 90 percent of those cases were in people who were not vaccinated.
Measles has been eliminated from the United States as 2000, and such a reversal would be “a source of great embarrassment,” Schaffner says. “To those of us who were involved early on in demonstrating that measles could be eliminated from large land areas, to have to seemingly turn back the clock and start all over in trying to convince parents that vaccinating their children is very, very important is very disheartening.”
Here’s what you need to know about measles elimination, and why experts are worried about the virus’ return.
Why is measles elimination critically important?
Measles is highly contagious. Roughly 95 percent of a community needs to be vaccinated or have immunity from a previous infection to stop measles from spreading. But not everyone can get a vaccine — as an example babies aren’t typically vaccinated until they are at least 1 year old. Eliminating measles through vaccination helps protect people who are still vulnerable.
A country’s whole population might not be affected if there’s a measles outbreak in a place that has mostly beaten back the virus, says epidemiologist Daniel Salas, executive manager of the Special Program for Comprehensive Immunization at the Pan American Health Organization. “but it’s going to affect some communities, some people, some families.” And many of those people can go on to have severe complications.
In the United States, about 1 in 5 unvaccinated people who get measles are hospitalized. Some develop serious complications from an infection, including pneumonia or vision loss. Others might experience immune amnesia, when the virus wipes out the body’s protection against other diseases, or deadly brain inflammation that can appear years later.
The outbreak in West Texas totaled more than 700 cases and killed two children,says Pedro Piedra,a pediatric infectious diseases physician at Baylor college of Medicine in Houston. “Now think about having millions of children get measles … numbers can escalate very quickly with regards to hospitalization,severity of disease and death.”
Can measles be brought back under control?
Vaccination is the best way to stop spread and prevent disease,experts say. Vaccine hesitancy and difficulties getting shots to the people who need them, however, are threatening progress.
It’s important to identify the barriers that prevent children from getting vaccinated, Salas says.Sometimes geographical barriers such as long treks to health care centers can pose problems. Language barriers or cultural or religious beliefs can also prevent people from seeking shots in general.
Community leaders can help navigate that terrain, working with experts to present a “joint front against thes diseases,” Salas says. But it can still be tricky to convince people to get vaccinated when they don’t see the devastation that measles can cause.
“If every parent had their eligible children vaccinated very quickly… these outbreaks of measles that we have around the country would be snuffed out immediately. It would happen dramatically,” Schaffner says. “That’s how good this vaccine is, if it’s used.”
Will occasional measles outbreaks be the new normal?
As long as measles sticks around in at least some places, even countries that have largely stopped the virus’s spread will be at risk. Only eradication — when the virus doesn’t infect anyone anywhere — would prevent outbreaks.
Because measles is so contagious, people who get infected abroad can spread the virus in communities with low vaccination rates and quickly cause an outbreak. In 2024, just 0.1 percent of global measles cases were documented in the Americas. But in 2025, that number has increased to more than 7 percent. “This is alarming for the Americas,” Salas says. “Because of [ongoing outbreaks] we have increased the percentage of cases globally.”
But vaccines have made the severity of measles infections fade from public memory, and some people might not fully understand what they are being protected from. It’s a bit like preparing for a hurricane, Piedra says. “You know the strength of a hurricane, but you don’t want to have to go through that to [know that you need to] prepare your home for the possibility of such strong winds.”
Falling vaccination rates meen the threat is growing. That the United States is on the brink of losing its measles elimination status, Piedra says, “is basically a failing grade for our health care system, for the protection of our children.”
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