The United States is in the middle of what’s shaping up to be the worst measles outbreak of this century.
Dylan Scott covers health for Vox, guiding readers through the emerging opportunities and challenges in improving our health. He has reported on health policy for more than 10 years, writing for Governing magazine, Talking Points Memo, and STAT before joining Vox in 2017.
The outbreak began within a small religious community in West Texas in January, but it has since spread across four states in the Southwest. Two school-aged children and one adult have died so far. The number of reported cases surpassed 1,000 this week, according to the latest data from the Centers for Disease Control and Prevention — though the real count may be much higher.
The challenge measles presents in 2025 is very different than in the years before a vaccine was introduced in the 1960s. In those days, we had limited defenses against the virus, which was highly contagious and highly dangerous to young children.
Today, we have perhaps the single best defense we have against any virus: a vaccine that is 97 percent effective in preventing measles, far better than vaccines against diseases like the flu or Covid. We have the means to snuff out measles. We’re just not using it, thanks in large part to an anti-science backlash that has gotten fresh momentum with the rise of vaccine skeptic Robert F. Kennedy Jr. to lead the nation’s health agency.
Now we’re in a dangerous moment of backsliding on decades of progress. How did it happen? The following four charts tell the story of how the US is losing the fight against measles — and why:
The January outbreak is now the single largest since the United States managed to eradicate, or end the disease’s natural spread in the country, in 2000: Texas has reported 709 cases, New Mexico 71, Kansas 49, and Oklahoma 17 — 846 in total, as of May 9. Since measles was eradicated, most cases in the intervening years have involved international travelers. The US saw more overall cases in 2019 — 1,274 in the final count — but that was the accumulation of several smaller outbreaks started by international travelers that affected Orthodox Jewish communities in New York City.
Some time this month, 2025 will likely surpass 2019 to officially become the worst year of measles overall in the United States since at least 1992, when there were about 2,100 cases.
When I spoke with infectious disease experts in February, as the current outbreak was just beginning to spread, they were concerned but not panicked. They expected the outbreak to remain largely contained to the isolated communities where it began, and that perhaps we would see a few hundred cases.
But we are well past that line now — and the spread has still been picking up speed.
There can be a long lag in measles cases being confirmed, but as more data comes in, it appears things are still getting worse. CDC data confirmed 111 new infections in the week starting March 30 — the single worst week for new measles cases in the US since the 1990s.
In 2000, the year the US declared measles eradicated, Americans were nearly unanimous in their belief that it was important for parents to get kids vaccinated against a host of diseases, measles included.
But that consensus has since weakened. Kennedy’s appointment underscores the national mood: The former presidential candidate spent much of the past 25 years spreading the debunked claim that childhood vaccinations lead to autism. And what had once been a fringe view is now in the seat of power.
In his role as head of US Health and Human Services, Kennedy has been as much a hindrance as a help. He has paid lip service to the value of vaccines in official statements, but continues to cast doubt on their safety in interviews and tout unproven, sometimes dangerous, alternative treatments.
Last week, Kennedy announced that the health department would investigate new therapeutics for measles, rather than putting his support behind the MMR shot, which is highly effective in preventing the disease and leads to better outcomes for patients who take it for the first time even after an infection starts.
Vaccination rates are declining in parallel with these attitudes, leaving us a long way from the “herd immunity” vaccination level necessary to contain the virus.
Experts say that 95 percent or more of an area’s schoolchildren need to be vaccinated in order to prevent measles from spreading widely. As recently as the 2019–2020 school year, more than 95 percent of kindergartners nationwide were vaccinated. But as of this year, that number has fallen below 93 percent.
And even that 93 percent nationwide figure is misleading. Fewer than a dozen states exceed the 95 percent threshold and, in some communities, the share of school-age kids who are vaccinated can be much lower. Some of the Gaines County, Texas, schools where the virus first took hold during the current outbreak had about half of their students protected against measles.
If you are an adult who believes you were vaccinated against measles and fear you may be in the way of the outbreak, there are steps you can take to double-check your immunity. If you’re a parent of a young child, it may be worth talking to your doctor about what your options are for getting your kid vaccinated early. I have 3-year-old twins who received their first dose around age 1 and, on the advice of their doctor, will get a second in the coming days, about a year ahead of schedule.
It’s the kind of precaution that would have been unthinkable — and wholly unnecessary — a decade ago. But things have changed. This is the new reality that we are living in.
Update, May 9, 2:10 pm ET: This story was originally published on May 7 and has been updated to note that cases in the measles outbreak have now surpassed 1,000.
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