The rise and fall (and rise again?) of measles in the United States (2025)

As the measles outbreak that began in West Texas continues to escalate—with the number of U.S. cases this year now surpassing all those recorded in 2024—so does misinformation about how the disease spreads and how to prevent it.

Despite claims from Health and Human Services Secretary Robert F. Kennedy Jr.that it’s“difficult” for measles to kill a healthy person, the American Academy of Pediatrics notes that healthy kids made up most of the measles deaths in the decades before a vaccine was developed.

And after the recent death of a six-year-old child in Texas, state officials there noted the child had no “known underlying conditions.”

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Meanwhile, the safest and most effective way to prevent measles was developed over 50 years ago: the measles vaccine. This hard-won scientific advancement helped eliminate the ongoing circulation of measles in the United States—but its benefits have been threatened in recent years with the increase in personal exemptions for school vaccine mandates.

In Texas, these exemptions are relatively easy to get, and several parts of the state have historically had very high exemption rates—including Gaines County, where the current outbreak began, says Rekha Lakshmanan, chief strategy officer for The Immunization Partnership in Houston. “We’ve been saying for quite some time that it was just a matter of time for an outbreak to happen in that part of the state,” she says.

Measles epidemics are tough to contain because the disease is so transmissible, says Peter Hotez, an infectious disease pediatrician and co-director of the Texas Children's Hospital Center for Vaccine Development. A paper Hotez wrote in 2016, about the possibility of measles spreading in the state, even specifically called out Gaines County as an area at high risk for a measles outbreak.

He says Texas health authorities are doing the best they can to get children vaccinated, but “the failure was the previous decade of failed policies that didn’t do enough to address anti-vaccine activism.” He adds, “It’s a full-on, organized anti-vaccine disinformation campaign, and Texas, unfortunately, is the tip of the spear for what’s happening nationally.”

But the continued spread of the measles isn’t inevitable—and, in some states, efforts are already underway to contain it.

The early fight against measles

“One of the things going on is this collective amnesia we have about diseases, mostly because a lot of us haven't seen measles sweep through a school or a family, and we don't appreciate how quickly the disease can move and how sick it can make our kids,” says Karen Ernst, director of the parent advocacy group Voices for Vaccines.

In the early part of the 20^th century, thousands of people died in the U.S. each year from measles. Improved medical care substantially reduced those deaths by the 1950’s, but the disease still killed an estimated 400 to 500 people a year while causing lifelong complications, like brain damage and deafness from measles-associated encephalitis, among hundreds of survivors.

And so scientist John Enders, fresh off his Nobel Prize-winning work contributing to the polio vaccine, made measles his next target. The first successful measles vaccine was approved in 1963, followed by a less reactive, improved one developed in 1968 by Merck scientist Maurice Hilleman and colleagues. Within a few years, measles cases dropped by about 90 percent nationwide, but it became clear that the existence of a vaccine by itself wasn’t enough to quash the disease.

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In the 1970s, former First Lady of Arkansas Betty Bumpers and former First Lady Rosalynn Carter pushed for states to require vaccination for public school attendance. By 1981, all 50 states required childhood immunizations.

Yet challenges remained, Ratner says. “Policy changes and influxes of funding would get more kids vaccinated and rates of measles would drop, and then the funding would go away, vaccination rates would drop, and measles cases would go back up,” he says.

The elimination of measles

The biggest wake-up call was a devastating measles outbreak in 1989-1991 that sickened over 55,000 Americans and killed 123. Philadelphia was among the hardest hit cities due to two churches that discouraged vaccination, but across the country, those who suffered most were Black and Hispanic children under age 5, particularly in inner cities.

Two things became evident. First, a single measles vaccine dose, at 93 percent effectiveness, was not enough. Second, if not all families could afford to be vaccinated, thousands of children would suffer, and too many would die.

Subsequently, the U.S. Centers for Disease Control and Prevention (CDC) and American Academy of Pediatrics began recommending two childhood doses of the vaccine, which increased effectiveness to 97 percent. President Bill Clinton also signed into law the Vaccines for Children program in 1994, which made all CDC-recommended immunizations free for children who could not afford them.

These two measures, along with school vaccination requirements, enabled the U.S. to achieve the 95 percent coverage necessary for herd immunity to prevent widespread outbreaks. The U.S. then eliminated measles in 2000, a designation that expanded to the rest of the Americas in 2016. (Elimination means a disease is no longer endemic to a region—but outbreaks can still occur if travelers contract it abroad and bring it back.)

In the meantime, two other threats emerged that allowed measles to creep back into the population. First, a fraudulent paper that tried to connect the measles vaccine to childhood developmental conditions frightened parents despite being later retracted and rejected by the scientific community. Then, the grassroots anti-vaccine movement inspired by that paper coincided with the rapid rise of social media, which helped spread misinformation more quickly and easily than ever before, says Richard Pan, a pediatrician and former California state legislator. “Social media is the fuel to the flame,” he says.

Measles rises again

Just as school mandates were key to eliminating measles in 2000, school exemptions have played a critical role in the reemergence of measles.

Every U.S. state offers medical exemptions for children with conditions that prevent them from safely receiving certain mandatory vaccines, such as an allergy to a vaccine ingredient. Most also have non-medical, or personal belief exemptions, with requirements to get these exemptions varying widely by state.

In 2006, researchers began documenting an increase in personal belief exemptions. These exemptions grew nationally from 1.75 percent in 2011 to 2.25 percent in 2016 and were more than twice as high in states with personal and religious exemptions compared to just religious ones—largely fueled by the rise of misinformation. While a 0.5-point national increase may seem small, it disguises how those exemptions are distributed.

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“When we look at overall immunization levels, that could be misleading if you've got clusters [of unvaccinated people] that are enough to sustain transmission, even if the overall population immunity is high,” says Walter Orenstein, a former associate director of the Emory Vaccine Center at Emory University.

Measles requires 95 percent of a community to be immune to prevent the disease from spreading. But the gradual two-decade rise in non-medical exemptions increased the likelihood of clusters of disease outbreaks, says Paul Offit, an infectious disease pediatrician and director of the Vaccine Education Center at Children’s Hospital of Philadelphia.

Those clusters often occur in communities that are “sequestered and religious,” Offit says, like the Mennonite community at the epicenter of the current Texas outbreak. Certain private schools, such as many Montessori and Waldorf schools in California, have also had higher rates of exemptions.

Such geographic clustering is what enabled measles to spread rapidly in a 2015 California outbreak, popularly called the “Disneyland outbreak,” that infected 147 people, capping off the previous year’s largest increase in measles cases since U.S. elimination.

The California outbreak “sent a signal that people should take measles more seriously now,” says Pan.

A new playbook to defeat measles

But public health experts knew the original approach that had helped the U.S. eliminate measles once—ensuring everyone could access an effective vaccine—wasn’t enough in this modern era of misinformation. The new front in the war against infectious disease is to address the vaccine waivers that allow clusters of cases to arise.

California had already attempted to restrict who could receive exemptions and improved the situation some, but clustering had remained a problem. In 2016, Pan introduced a bill in California to eliminate the state’s non-medical exemptions. After the bill passed, measles vaccination coverage rose, with the biggest gains in counties with the lowest rates—the clusters. Within a year, the number of counties without herd immunity was cut in half.

But an expected result occurred: though overall exemptions fell, medical exemptions—which had remained stable for the previous two decades—began increasing. Some schools had “extraordinarily high” exemption rates, Pan says, but a “very small number of physicians” were writing nearly all the exemptions.

So in 2019, California passed yet another law that required state oversight of medical exemptions. Medical exemptions then fell from 0.95 percent that year to 0.27 percent in 2021.

“I think California is in a much better place,” Pan says. “We’ve had measles still show up, but we haven’t had any outbreaks.”

Other states have since followed suit. Northe Saunders, executive director of SAFE Communities Coalition & SAFE Action Fund, successfully led a campaign to remove all personal belief exemptions in Maine in 2019, which they then defended through a state-wide referendum in March 2020.

“It was parents standing on the shoulders of professionals, amplifying the voices of pediatricians and public health experts and saying, I’m a parent, I care about my kids, and I trust my doctor,” Saunders says.

Similar campaigns have eliminated non-medical exemptions in Connecticut and New York, and Washington removed them only for the measles-mumps-rubella vaccine.

What parents need to know today

But even as some states eliminate vaccine waivers, Saunders warns that the anti-vaccine movement is pushing to expand them, as evidenced by the vaccination bills in states across the U.S. right now.

“That’s why it’s important for parents to get a little bit more vocal about the fact that they do vaccinate their kids,” says Ernst. Although choosing not to vaccinate has become less of a fringe position since the pandemic—with many people emphasizing their personal freedoms alongside the rise in vaccine misinformation—she points out that the vast majority of parents do vaccinate their children.

Still, the decline in national immunization rates caused by missed vaccinations during the COVID-19 pandemic and spillover of pandemic vaccine hesitancy into childhood vaccines present big challenges to parents who want to see immunization rates remain high in their communities. Several states with personal exemptions are among those with current cases as the disease has spread from nine to 19 states in just four weeks.

Meanwhile, ProPublica revealed on March 28 that CDC leaders quashed the release of an assessment on the current measles outbreak—created by the agency’s internal forecasting center—which found that while the risk of catching the disease remains low for the general public, it is high in areas with lower vaccination rates near the current hot spots. The CDC noted internally that it had moderate confidence in the assessment and was still investigating the spread of the illness in West Texas, ProPublica reported.

The agency issued a written statement to ProPublica noting that it did not release the assessment “because it does not say anything that the public doesn’t already know.” It added that it still regards vaccines as “the best way to protect against measles” but, in an echo of language recently used by RFK Jr., it asserted that “the decision to vaccinate is a personal one” and that “people should consult with their healthcare provider to understand their options to get a vaccine and should be informed about the potential risks and benefits associated with vaccines.”