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Jennifer
B. Nuzzo[/caption]
In the three decades between 1993 and 2024, measles in the U.S. was relatively rare – a few hundred cases each year, at most.
As of March 2026, measles has been continuously circulating around the U.S. for more than a year, starting with an outbreak in Texas that lasted from January to August 2025. Before that outbreak was declared over, an outbreak on the Utah and Arizona border began in August and is ongoing. An outbreak in South Carolina began in September, drastically increased in January 2026, and continues.
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Andrea Uhlig[/caption]
Thirty states have had measles cases this year; 47 have seen cases since the start of 2025. Health officials across the U.S. have confirmed 1,300 infections already this year as of March 6, putting the country on track to surpass 2025’s numbers, which were the highest in 35 years.
We study outbreak preparedness and response at Brown University’s Pandemic Center, and we view the return of measles in the U.S. as a grim signal of what’s to come.
Low levels of vaccination across the country mean measles outbreaks will continue to occur, needlessly hospitalizing and killing the unvaccinated. But beyond these harms, the disease’s resurgence serves as a serious warning about the country’s capacity to manage infectious-disease threats of all kinds.
Measles’ return is no mystery: At its root is the falling vaccination rate.
Around 90% of the U.S. population has received the MMR vaccine, which protects against measles, mumps and rubella. In some regions, the rate is below 60%. Since about 2019, that overall number has dropped below the 95% needed for herd immunity. It is necessary to keep that rate nationally, but maintaining herd immunity at the local level is equally important to prevent measles from finding pockets of unvaccinated communities.
By any measure, the U.S. measles outbreaks signal that the disease has returned in a way that will have serious health consequences. In 2025, three people died from measles in the U.S. That is more than in any year since the disease’s elimination 25 years ago.
Of the country’s 2,283 confirmed measles cases in 2025, 11% were sick enough to be hospitalized.
People who recover from measles can experience complications such as pneumonia or encephalitis, which can later lead to deafness or intellectual disabilities from the brain swelling. The virus can also affect the immune system, making people more susceptible to other infections.
In rare instances – though more likely if someone is infected as a child – measles patients can develop a progressive dementia known as subacute sclerosing panencephalitis, or SSPE, anywhere from two to 10 years after their infection. SSPE always leads to death. This past year, a child in Los Angeles died of this condition years after being infected with measles as an infant, before they were old enough to be vaccinated.
Recurring outbreaks of measles will mean high economic costs.
Studies have found that the cost of containing measles outbreaks is often as much as tens of thousands of dollars per case. The Common Health Coalition found that a sustained 1% drop in MMR coverage would cost the U.S. billions across health care systems and the economy.
As concerning as recent outbreaks have been, they herald a larger systemic problem.
How a country controls measles can be viewed as a proxy for how well it would control other diseases. That’s because the steps for stopping the spread are the same: deploying vaccines to prevent infections, detecting and isolating cases when they occur, identifying exposed contacts of infected people and making sure they stay home if they’re likely to be contagious, and treating sick people safely.
Controlling the spread of many infectious diseases depends on the public’s trust in the basic components of public health. Declining MMR vaccine coverage reveals underlying challenges in public support for vaccines. Public confidence in the Centers for Disease Control and Prevention is also eroding, according to polling from 2023 to early 2026 by the health policy organization KFF. Less than half of the people polled trust the government even “a fair amount” to provide reliable vaccine information.
These growing cracks in the public health armor will complicate efforts to protect Americans from future threats – whether an outbreak, a pandemic, or a biological attack.
Jennifer B. Nuzzo is a professor of epidemiology and director of the Brown University Pandemic Center. Andrea Uhlig is a research assistant at the center. Distributed by The Conversation and The Associated Press.
