Why U.S. Measles Outbreaks Have Grown Harder to Extinguish

The nation is already nearing last year’s record case total, and experts say the virus is forcing doctors to relearn a disease many thought had been consigned to history.

July 6, 2026 at 5:00 a.m. EDT

Summary

A measles, mumps and rubella vaccine is administered to a 1-year-old in Seattle last year. (Lindsey Wasson/AP)

By Lena H. Sun

The United States is on the brink of surpassing last year’s total measles cases, putting the country on track to set a new record before summer’s end.

The impending milestone underscores how the country has entered a new phase in its battle with measles, with repeated new infections of the deadly disease igniting sustained outbreaks in multiple states rather than staying concentrated in a few undervaccinated communities.

Since an unvaccinated child in West Texas developed measles early last year, successive outbreaks have sickened thousands of people and have now spread to 39 states, the District of Columbia and New York City. Last year, the U.S. reported 2,288 measles cases, the highest since measles was eliminated in 2000 and the most in more than three decades. The U.S. is now poised to reach that level in roughly half the time, with 2,170 measles cases as of July 2, according to the CDC.

As vaccination rates decline and measles spreads wider, those outbreaks are becoming harder to extinguish. There are fewer people to investigate cases, communities most affected often remain difficult to reach, and a generation of doctors is getting a crash course in diagnosing and managing a disease many have rarely — if ever — encountered. State health officials fear their outbreaks may never end and say the actual number of cases is far higher than official counts reflect.

“Maybe we’ll get it under control here in Utah, but other states will go through what we just experienced, and then it will come back here,” said Utah state epidemiologist, Leisha Nolen. Utah is now home to the largest active outbreak. “I have concerns that this could be the future for a while.”

Utah’s measles outbreak, which began in an isolated community along the Arizona border in June 2025, has spread into nearly every county in the state. Although transmission has slowed, Nolen worries new “introductions,” the initial establishment of a disease into a new geographic region, could reignite it when schools reopen. More than 680 people have been sickened, with more than 500 infections this year.

A genetic analysis suggests the true number of Utah’s cases is probably four times higher, Nolen said.

Health officials in Virginia, Pennsylvania and other states have similar fears about continued introductions.

“I think we’ve seen a threshold where there are introductions happening all the time, all over the place,” said Andrew Pavia, an infectious-disease physician and professor of pediatrics and medicine at the University of Utah.

Public health officials and infectious-disease experts say several factors account for the rapid spread of measles this year.

Doctors confront a disease they have never seen

In a sign of how seriously physicians view the threat, more than a dozen medical and public health organizations launched an unusual effort this month to help prepare doctors and hospitals for a disease many practicing physicians have rarely — or never — encountered but may now need to manage as part of everyday practice.

“Clinicians really haven’t thought about measles,” said Patsy Stinchfield, executive director of the new group, the Measles Collaborative. “They skipped that chapter in medical school” because the U.S. eliminated the disease more than a quarter-century ago, she said. “And here they are now, having to diagnose it.”

The group, established by the National Foundation for Infectious Diseases, is developing an app to help doctors diagnose measles. It is creating hospital checklists and clinical algorithms to guide the complicated logistics of safely caring for patients. Because the virus can remain suspended in the air for up to two hours, hospitals must carefully determine where patients are evaluated, isolated and treated.

To counter misinformation on social media, the group plans to create TikToks and Instagram posts for parents to explain the basics of measles, including how sick children can get.

Most children recover after several miserable days of fever, cough, congestion and pink eye.

But measles can also cause pneumonia, brain swelling, deafness, intellectual disability and death. It can trigger a rare but invariably fatal brain disease, subacute sclerosing panencephalitis, or SSPE, years after the initial infection.

Pavia worries many parents still underestimate how sick measles can make children.

“People aren’t really motivated by fear of the rare, terrible thing,” said Pavia, who has cared for children hospitalized for measles. “What I think would help much more is if people realized that they would see their 4-year-old sicker than they’ve ever been. Moaning and crying in bed or needing to be hospitalized for two or three days on oxygen, fighting to breathe.”

Some doctors worry about what happens after children recover.

Measles can erase immune memory, leaving children temporarily vulnerable to infections such as influenza and covid-19 — even if they had previously been vaccinated or infected. Those infectious diseases could result in a whole new set of complications. In recent years, the country has seen some of the highest numbers of flu deaths among children in decades.

“That means those people who get measles now get to have flu, get to have covid, essentially as if they were getting those infections for the first time,” Nolen said.

Vaccination rates keep falling

Vaccination rates have fallen across the country since the pandemic. At the same time, the share of children claiming religious and other exemptions from vaccine requirements is at an all-time high, according to federal data.

Two doses of the childhood measles, mumps and rubella (MMR) vaccine are 97 percent effective against infection and nearly wiped out a virus that once infected millions of children. But because the virus is so easily transmitted without immunization, 95 percent of a community needs to be vaccinated for herd immunity, the level needed to prevent isolated cases from becoming outbreaks.

The basic reproduction number calculates a range of the number of people who will contract an infection from every one person with the virus. Below shows the maximum of the infection range for each disease.

Nationwide, 92.5 percent of kindergartners had received the measles vaccine in the 2024-2025 school year, lower than the previous year.

Before the pandemic, about half of U.S. counties met the 95 percent threshold among kindergartners. By the 2024-2025 school year, fewer than 3 in 10 did, according to a Washington Post examination of public records.

In Utah, only 88.6 percent of kindergartners had received the MMR vaccine for the 2024-2025 school year, according to state health department data, compared with 92.7 before the pandemic.

Nationally, 3.6 percent of kindergartners claimed vaccine exemptions in 2024-2025. In Utah, for the 2025-2026 school year, the rate was 12.7 percent, and in the Southwest health district where the outbreak began, rates have soared: 27.1 percent of children had an exemption.

When measles reaches those pockets of unvaccinated children, Nolen said, “it can easily take off.”

The rise in vaccine hesitancy has affected vaccine-preventable diseases beyond measles.

For example, cases of pertussis, or whooping cough, which is highly contagious, have been on the increase nationally. UCHealth, the largest health system in Colorado, has already confirmed 168 pertussis cases in the first six months of 2026 — surpassing the 126 cases recorded during all of 2025, said Michelle Barron, UCHealth’s senior medical director for infection prevention and control.

Health departments are stretched

Once the measles virus starts spreading, health departments rely on labor-intensive contact tracing, case investigations and quarantine measures to keep outbreaks from growing. But public health officials say recent federal funding cuts have left many departments with fewer people to do that critical work.

Despite the rapid resurgence in measles activity across the country, outbreak control capacity of health departments in the U.S. has not recovered or expanded.

“We didn’t increase our preparedness and our ability to fight measles,” Pavia said.

When South Carolina was battling an outbreak that ultimately sickened 997 people, most of them this year, the health department had lost dozens of epidemiologists, infection preventionists and other public health staff as a result of federal funding cuts, said Linda Bell, who recently retired as state epidemiologist.

“That was just very taxing for the remaining staff,” Bell said in an interview.

South Carolina scrambled to hire temporary staff, but Bell said the reinforcements couldn’t replace the expertise that had been lost and officials ultimately shifted from containment to mitigation.

The virus surged through dozens of schools in Spartanburg County, the outbreak epicenter, which long had lower childhood vaccination rates than much of the state. Students were sent into quarantine multiple times before the outbreak was declared over in April. Schools that required multiple rounds of quarantine had average vaccination rates of 77 percent, according to a recent study by Cornell University researchers.

Researchers said South Carolina’s outbreak reflected a pattern seen repeatedly in the U.S., in which faith communities with shared views on vaccination sustain and amplify transmission. Twenty-nine cases were linked to one church.

“I think that we transitioned from containment to mitigation because we saw ongoing spread for weeks and weeks,” said Bell, who retired in April.

Different states, different responses

Public health officials say one of the biggest challenges is navigating communities that no longer trust government or health institutions, forcing authorities to carefully tailor messaging or consider what people are willing to do for the public good.

But individual states have different systems and different playbooks.

As cases spread across Utah, local health districts avoided using the word “quarantine,” fearing it would trigger negative feelings from lockdowns and restrictions during the covid pandemic. Some places used the term “school exclusion” instead to encourage unvaccinated children to stay home after exposures, Nolen said. But that phrasing likely dulled the urgency of the message, public health experts say.

One local health district opted to have only the unvaccinated children at highest risk — classmates or children on the same bus as an infected child — stay home.

The standard — and safest — public health approach would have been to keep all unvaccinated children home, said Ellie Brownstein, president-elect of the Utah chapter of the American Academy of Pediatrics.

But that approach would not have been accepted by all communities, Nolen said.

“If we go for things that are unrealistic and unacceptable, we have no possibility of doing our job,” Nolen said.

Nolen said the challenge isn’t more messaging but rebuilding connections with communities that don’t engage with traditional public health communication.

“I do strongly believe part of the flaws with public health is we just aren’t connecting with everyone,” Nolen said.

After she visited the hardest-hit communities in southwest Utah, where distrust of government runs deep and childhood vaccination rates are low, residents told her they weren’t anti-vaccine. They just didn’t know who to trust, Nolen said.

Many told her they felt judged when they sought medical care. Had they felt more welcome, “they might have actually eventually gotten to the point where they could trust somebody and have a conversation that would make them feel confident about getting vaccinated,” she said.

In South Carolina, the centralized health department allowed officials to direct resources to the Spartanburg area. Standardized response protocols meant epidemiologists anywhere in the state followed the same response playbook, Bell said.

Bell also held 26 weekly media briefings, starting in October, throughout the outbreak, which she said helped inform the public and probably encouraged vaccination.

But rebuilding trust has become even harder because health officials are now confronting not only the disease itself but also misinformation.

Messages from elected and appointed leaders who reject evidence-based public health recommendations have undermined outbreak responses, said Bell, who did not identify officials by name. Since taking office, Health Secretary Robert F. Kennedy Jr. has questioned vaccine safety, reshaped federal vaccine policy and criticized long-standing vaccination recommendations.

“In the past ... we were battling the diseases,” Bell said. “We were not battling this misinformation that is now coming from an entirely different stream that is within the federal government.”

Naema Ahmed, Jenny Ye and Dylan Moriarty contributed to this report.