U.S. Measles Cases Pass 4,000 for the First Time, CDC Reports, Far Above 2025

The number of measles cases in the United States this year has topped 4,000, a record, the Centers for Disease Control and Prevention reported Friday. The agency said there were 4,080 confirmed cases across the country as of Thursday.

That total is far above the 2,289 cases recorded in all of 2025. Last year was itself the worst in three decades. Most states and Washington, D.C., have now reported cases of the highly contagious disease.

Pennsylvania has been the center of the outbreak. The state surpassed 1,000 total cases this week after reporting 145 new cases on Wednesday alone. According to the Pennsylvania Health Department, there have been five measles-associated deaths in the state this year. The department counts a death as measles-associated when a person dies within 30 days of experiencing symptoms, with clinical evidence of an infection and a positive lab test, and when the death is not due to unrelated causes such as a car accident.

In neighboring New York, Gov. Kathy Hochul declared an emergency on Monday over the rising number of cases in the region. Her executive order allows more health care professionals to administer measles vaccines and lets nurses order testing, according to the governor's office. The order is aimed at widening the number of people who can vaccinate and test as demand grows.

The CDC's data underline how much vaccination status matters. According to the agency, 95% of patients nationwide this year were unvaccinated against the disease or their vaccination status was not known. About 2% of patients had received one dose of the measles, mumps and rubella vaccine, and another 2% had received two doses.

Measles symptoms typically appear between one and two weeks after a person comes into contact with the virus, the CDC says. The first signs are high fever, cough, a runny nose and red, watery eyes. Two to three days later, tiny white spots may appear inside the mouth. A rash then breaks out three to five days after the first symptoms appear.

The disease spreads easily through the air, and an infected person can pass it on before the rash appears. That is one reason outbreaks can grow quickly once they take hold in communities with low vaccination rates.

The numbers leave the country far past the level reached last year, when health officials were already calling the outbreak the worst in a generation. With Pennsylvania adding well over a hundred cases in a single day this week and New York now under an emergency declaration, officials in both states have been working to expand testing and vaccination capacity. The CDC updates its national count weekly.