In the three decades between 1993 and 2024, measles in the US was relatively rare – a few hundred cases each year, at most. But suddenly the disease has become so entrenched in American life that it sometimes fails to make headlines when a new outbreak breaks out.
As of March 2026, measles has been continuously circulating around the United States for more than a year, starting with a outbreak in Texas which lasted from January to August 2025. Before that the outbreak was declared overone outbreak in Utah and Arizona border began in August and is ongoing. An outbreak in South Carolina began in September, increased drastically in January 2026, and continues.
30 states have had measles this year; 47 have seen cases since the start of 2025. Health officials across the United States have confirmed 1,300 infections already this year on March 6, putting the country on track to surpass the 2025 figures, which were the highest in 35 years.
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We study outbreak preparedness and response on Brown University’s Pandemic Centerand we see the return of measles in the United States as a grim signal of things 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 damages, the disease’s resurgence serves as a dire warning about the country’s capacity to deal with infectious disease threats of all kinds.
An eliminated disease returns
Measles’ return is no mystery: the root cause is declining vaccination rates.
About 90% of the American population has received MMR vaccine, which protects against measles, mumps and rubellaand in some regions of the country, the rate is below 60%. Since about 2019-2020, the total number has fallen below the 95% needed for herd immunity. It is necessary to maintain that rate nationally, but maintaining herd immunity at the local level is equally important to prevent measles from finding pockets of unvaccinated communities.
Countries that remain free of continuous transmission for 12 months considered to have eliminated measles – a designation the United States achieved in 2000. The Pan American Health Organization was scheduled to decide in April whether the United States should lose that designationbut the organization postponed the meeting until November.
Current trends suggest that both the United States and Mexico, which have also battled the disease, may lose this status – as Canada did so in November 2025. All three countries have seen their vaccination rates fall below the 95% thresholdand their outbreaks may share epidemiological links.
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A serious, long-term threat to America’s health
Regardless, the ongoing US measles outbreaks signal that the disease has returned in a way that will have serious health consequences. In 2025, three people died of measles in the USA It has been more than in any year since the disease was eliminated 25 years ago.
Of the country’s 2,283 confirmed cases of measles in 2025, 11% were ill enough to be admitted to hospital. In South Carolina, where most cases of measles have been reported in 2026, hospitals are not required to report when patients are admitted for measles complications, so the actual number of hospitalizations due to measles may be much higher.
People who recover from measles may experience complications such as pneumoniawhich can lead to death, or encephalitiswhich can later lead to deafness or intellectual disabilities from brain swelling. The virus can too affect the immune systemwhich makes people more susceptible to other infections in the long term, even those they have had before.
In rare cases – but more likely if someone is infected as a child – measles patients can develop a progressive dementia known as subacute sclerosing panencephalitisor SSPE, anywhere from two to 10 years after the infection. SSPE always leads to death. In the last year, a school-age children in Los Angeles died of this condition years after they were infected with measles as infants, before they were old enough to be vaccinated.
Measles is an economic nuisance
Repeated outbreaks of measles in the United States will mean high economic costs. Countries have sought to eliminate measles in part because of the clear economic benefits of stopping domestic transmission of the virus.
Studies have found that the costs of containing measles outbreaks are often as much as tens of thousands of dollars per case. One outbreak in Washington state in 2018-2019involving 72 cases — a small outbreak compared to what states now report — cost $3.2 million in public health response, medical expenses and lost productivity. The Joint Health Coalition found that a sustained 1% drop in MMR coverage would cost the US billions across the health care system and the economy.
An opening for infectious diseases
As worrisome as recent outbreaks of measles have been, they portend a larger systemic problem.
How a country controls measles can be seen as a proxy for how well it would control many other diseases. That’s because the steps to stop the spread are the same: deploy vaccines to prevent infections, detect and isolate cases when they occur, identify at-risk contacts of infected people and ensure they stay home if they are likely to be contagious, and treat sick people safely.
But besides measles, we have already seen infections that were once controlled, like whooping coughwhich rose sharply in 2024 and remained high in 2025 compared to before the COVID-19 pandemic.
That’s because controlling the spread of many infectious diseases depends on public confidence in the basic components of public health. Falling MMR vaccine coverage reveals underlying challenges in public support for vaccines. Public confidence in the current Centers for Disease Control and Prevention also erodes, according to opinion polls from 2023 to early 2026 by the health policy organization KFF. Less than half of the respondents trust the government to even “a good deal” provide reliable vaccine information.
These growing cracks in the nation’s public health armor will complicate efforts to protect Americans from future disease threats — whether an outbreak, a pandemic or a biological attack.
This edited article has been republished from The conversation under a Creative Commons license. Read original article.
