By Jennifer Calfas

Measles cases in the U.S. during the first seven months of this year have surpassed all of 2025's tally, setting a new three-decade high.

The Centers for Disease Control and Prevention on Friday reported 2,318 confirmed cases of measles so far this year, exceeding the number of cases in all of 2025. Its rapid spread illustrates a new normal in the U.S., where falling vaccination rates have made more communities vulnerable to the highly infectious disease that the country declared eliminated more than 25 years ago.

Outbreaks in Utah and South Carolina contributed to around half of the country's total cases, according to CDC data. Each state handled it differently. South Carolina's health department required unvaccinated students exposed to measles to quarantine for three weeks after possible exposure and eventually declared the outbreak over within seven months. Utah's ongoing measles outbreak, fueled in part by a lack of uniform quarantining efforts, has lasted more than a year and spread to nearly every county in the state.

Measles cases are also currently on the rise in Pennsylvania and Virginia.

Since the early 1990s, the U.S. has recorded just a few dozen or hundred cases of measles each year. These back-to-back years of thousands of cases set the stage for the country to lose its measles elimination status that it achieved in 2000 thanks to aggressive vaccination drives and federal initiatives, including the Vaccines for Children program, which made shots free for millions of children.

Nationwide, kindergartners' vaccination rates for measles, mumps and rubella, commonly referred to as MMR, dropped to 92.5% in the 2024-25 school year, from 95.2% in 2019-20, according to the CDC. That means the country's youngest elementary schoolers are no longer vaccinated to the 95% level that constitutes herd immunity, which is achieved when enough people are vaccinated that it becomes more difficult for an infectious disease to spread.

The generally high vaccination rate nationwide is keeping these outbreaks from getting worse, said Amira Roess, a global health and epidemiology professor at George Mason University's College of Public Health. But the national rates don't show the full picture. Vaccination rates have significantly decreased over the last 30 years in small pockets of the country, she said.

"More and more of the younger kids are showing up to school unvaccinated or undervaccinated, and therefore susceptible," Roess said. "It's sort of like brush. Fire will come in, and it will go through it very rapidly."

Vaccination rates are dramatically lower in some states, communities and schools. In Idaho, 78.5% of kindergartners received the MMR vaccine ahead of the 2024-25 school year -- the lowest share of any state. In the northern part of South Carolina, where a measles outbreak spread earlier this year, one school reported just around 20% of its students had all the required vaccinations.

"We may and most likely will continue to see these smaller outbreaks in these communities as the virus continues to spread," said Dr. William Moss, a professor at the Johns Hopkins University Bloomberg School of Public Health.

The Pan American Health Organization is scheduled to determine in November whether the U.S. has lost its measles-elimination status. Measles is considered eliminated when there is no endemic spread for at least 12 months.

"It's not a trivial thing to lose elimination status," said Dr. Walter Orenstein, former director of the U.S. National Immunization Program at the CDC. "It means measles is endemic in our country, and anybody can get exposed."

Infectious-disease specialists have criticized the Trump administration's response to measles outbreaks, saying federal health leaders could more directly urge MMR vaccination. Dr. Ralph Abraham, who served as the CDC's principal deputy director for less than three months earlier this year, told reporters in January the possible loss of elimination status is "just the cost of doing business" with other countries.

"Our goal should be to not tolerate 2,000 infections but to shoot for zero," said Dr. Demetre Daskalakis, former director of the CDC's National Center for Immunization and Respiratory Diseases who resigned last year over issues including changing vaccine policy. "A really good question that folks should think about is: Has the United States changed its policy without telling us?"

Write to Jennifer Calfas at jennifer.calfas@wsj.com

(END) Dow Jones Newswires

July 24, 2026 11:23 ET (15:23 GMT)