US Measles Surge Tops 3,470 Cases in Worst Outbreak in Decades

The United States measles outbreak has reached 3,471 cases this year after the Centers for Disease Control and Prevention added 177 infections in its latest weekly update. The increase marks the sixth consecutive week of triple-digit growth, and the country is now living through its worst measles year in more than three decades. The measles surge shows no sign of slowing as autumn begins, with weekly case counts still climbing into the triple digits.

The 2026 total already sits 52 percent above last year's count of 2,289 cases, with more than three months of the year left, according to the University of Minnesota's Center for Infectious Disease Research and Policy. The comparison with recent years is stark: 285 cases in all of 2024, and 59 in 2023. Infections have been confirmed in 45 states plus New York City and Washington, D.C.

Four reported deaths still unconfirmed

Pennsylvania's health department has reported four measles-related deaths this year, two of them in babies and two involving adults, but the CDC's weekly tally does not acknowledge any of them. The agency now says measles deaths must be confirmed by the National Center for Health Statistics, a process normally used to track long-term disease trends rather than new deaths, and the extra step has substantially delayed confirmation, CIDRAP reported.

Pennsylvania has become the center of the outbreak. The state added 93 cases in the past week, 36 of them in two days, bringing its 2026 total to 767 infections. Lancaster County accounts for 324 of those cases, followed by Mifflin with 93, Chester with 72 and Snyder with 35. More than 99 percent of Pennsylvania's patients were unvaccinated or undervaccinated, and about one in five has needed hospital care.

Who is getting sick

Nationally, nearly all cases were acquired locally; only 17 of this year's total trace back to international travel. Eighteen percent of patients are children younger than five, and 62 percent are children and teenagers. Nine percent of patients have been hospitalized, up from eight percent the week before. Nationwide, 95 percent of measles patients are unvaccinated or have an unknown vaccination status, the CDC said.

The agency now lists 39 active outbreaks, defined as three or more related cases, one more than last week. South Carolina is listed with 670 infections this year, even though the state's large outbreak spanning 2025 and 2026 was declared over on April 27. Utah follows with 527 cases, then Texas with 192, Virginia with 178 and Wisconsin with 158. Ohio confirmed 47 new cases this week for a state total of 180.

The current measles surge has already rewritten recent records. Last year's total was itself the most since 1991, and the country passed it in July. South Carolina's outbreak produced 997 cases across 2025 and 2026 before officials declared it over, the largest single state outbreak in the modern tally. Utah counts 518 cases by its own records, nine fewer than the CDC's figure, a reminder that state and federal tallies can differ during fast-moving outbreaks.

A global comparison

Measured per capita, the United States has recorded 13.2 measles cases per one million people through mid-September, according to World Health Organization data cited by FactCheck.org. That rate puts the country 65th highest among 169 nations with available data, inside the worst 38 percent and about even with Russia. FactCheck ran the numbers after Health and Human Services Secretary Robert F. Kennedy Jr. said the United States was controlling the outbreak better than any other country.

Jennifer Nuzzo, director of the Pandemic Center at Brown University, called it the "worst bout of measles" the United States has seen in more than 30 years. KFF's Josh Michaud said peer developed countries have essentially no outbreaks at all. Pennsylvania's health department said the best protection against measles remains getting fully vaccinated, noting that two doses of the MMR vaccine provide 97 percent lifetime protection.

CIDRAP documented the full weekly breakdown in its report on the latest CDC update, including the state-by-state counts and the dispute over confirming the Pennsylvania deaths.

You can follow continuing coverage of the outbreak in our Health section, along with reporting on infectious disease research in Science. The per-capita comparison drew on FactCheck.org, which tracks official case data alongside the CDC.