U.S. Measles Cases Top 4,850, the Most Since Before the Disease Was Declared Eliminated

The United States has recorded more measles cases in 2026 than in any year since 1991, according to federal data updated this week, as a resurgence that began nearly two years ago in West Texas continues to spread through communities with falling childhood vaccination rates.

The Centers for Disease Control and Prevention reported 4,852 confirmed cases as of Oct. 29, up from 4,588 a week earlier. The agency's count includes cases in 47 states and jurisdictions plus 18 among international visitors. It is more than double the 2,289 cases reported for all of 2025, and more than 17 times the 285 cases recorded in 2024, the year before the current outbreak began.

A fast-moving outbreak enters its second year

Ninety-six percent of this year's cases are linked to one of 43 outbreaks the CDC has tracked in 2026. Of those outbreak-linked infections, roughly 1,400 trace back to chains of transmission that first ignited in 2025 and never fully stopped, according to the agency's running case data. That distinction matters: the original outbreak, centered on an undervaccinated Mennonite community in Gaines County, Texas, began on Jan. 20, 2025. Under international rules, a country loses its measles elimination status if a single chain of transmission runs uninterrupted for 12 months or more.

The Pan American Health Organization, which verifies elimination status for the Americas, had planned to rule on the U.S. case by mid-April but pushed the review to November, citing the complexity of the genomic sequencing needed to determine whether later outbreaks in states including Utah, Arizona and Pennsylvania are truly offshoots of the Texas strain or separate introductions. Canada lost its own elimination status in November 2025 after PAHO concluded its outbreak met that same 12-month threshold. The U.S. was declared free of endemic measles transmission in 2000, a status the CDC's own history of the disease describes as one of the signature achievements of the national vaccination program; before that, measles hospitalized an estimated 48,000 Americans and killed 400 to 500 every year.

Vaccination gaps are widening

The outbreak is unfolding against a backdrop of declining childhood immunization. Kindergarten MMR vaccination coverage nationally fell to 92.4 percent for the 2025–26 school year, below the roughly 95 percent public-health officials consider necessary to prevent sustained spread, while the share of kindergartners with a nonmedical exemption rose to a record 4.2 percent, up from 3.6 percent the year before, according to CDC data released in August. Twenty-four states now report exemption rates above 5 percent, and only 10 states have MMR coverage above the 95 percent threshold, compared with 19 states five years ago.

The practical effect is visible in several states at once. New York Gov. Kathy Hochul declared a statewide disaster emergency on Oct. 5 after measles spread through 18 mostly rural, under-immunized counties, a step intended to widen who can administer MMR vaccine, including paramedics, pharmacists and midwives, and to speed reporting of new doses to immunization registries. In Wisconsin, state health officials have logged 267 cases so far this year, with an outbreak in four southwestern counties that continues to add cases weekly among people who were not vaccinated. Pennsylvania's outbreak, centered in Lancaster County, has become the state's largest in decades. In an earlier CDC tally, when the national count stood at 4,588, the agency reported that about 1 in 10 patients had required hospitalization and that 96 percent were unvaccinated or had an unknown vaccination status, figures drawn from that week's federal data. Most patients nationally have been children and teenagers.

"Halfway into 2026 the U.S. is experiencing the worst year for measles since 1991."

That assessment came from Dr. Andrew D. Racine, president of the American Academy of Pediatrics, in a statement issued by the organization over the summer, when the national total had just surpassed 2,318 cases. Racine said two doses of the MMR vaccine remain about 97 percent effective at preventing infection, and described the toll in plain terms: infants hospitalized with pneumonia, students missing weeks of school to recover or to clear quarantine, and parents missing work to care for sick children.

What comes next

The immediate question is whether the outbreak will cost the country its elimination status. PAHO's Regional Verification Commission is scheduled to take up the U.S. case during its annual meeting this month, a year and roughly nine months after the Texas outbreak began. The commission's recommendation goes to PAHO's director, who formally notifies national health authorities of any change in status; a loss of elimination status would be largely symbolic in the short term — it carries no automatic penalty — but public-health researchers say it could complicate international reporting and reputation, and it would make the U.S. the second country in the region, after Canada, to lose a designation it has held for a quarter century.

In the meantime, state and local health departments are bracing for the cases that typically follow holiday travel and family gatherings in November and December, when relatives from under-vaccinated communities and international visitors mix more than usual. The CDC continues to recommend that children receive their first MMR dose at 12 to 15 months and their second at 4 to 6 years, with earlier doses available for infants traveling internationally, and that adults confirm their own vaccination history before holiday travel.