US Measles Cases Reach 4,410 as CDC Sends More Help to Pennsylvania

The Centers for Disease Control and Prevention reported 4,410 confirmed measles cases in the United States as of Oct. 15, an increase of 330 cases from its update a week earlier, Reuters reported on Friday. The new count keeps 2026 far ahead of last year. The CDC counted 2,289 cases in all of 2025.

Cases came from 47 jurisdictions, with 4,392 cases reported by states and cities and 18 cases among international visitors to the United States, the CDC said on its measles data page, updated Oct. 16. The agency counted 42 new outbreaks in 2026, and said 96 percent of confirmed cases, 4,228 of 4,410, are linked to outbreaks. Hospitalizations this year stand at 451, Reuters reported.

Pennsylvania is the center of the outbreak

Pennsylvania has reported 1,222 measles cases this year as of Oct. 14, with 225 hospitalizations linked to the disease, according to state health department data cited by Reuters. The state has reported five measles related deaths.

The CDC said on Tuesday it would deploy more support to Pennsylvania to help investigate the outbreak, Reuters reported. Earlier this month, New York declared a disaster emergency for the measles outbreak, the first such declaration by a US state, according to Reuters.

Why the death counts differ

Pennsylvania counts five deaths, while the CDC has confirmed two measles associated deaths in 2026 and has not identified the states involved, Reuters reported. Last month, the CDC shifted to using mortality data from the National Center for Health Statistics for measles related deaths, rather than relying on state health departments, a change that has drawn scrutiny.

The CDC says its death total is subject to change as reviews are completed. The agency also says it is working with the Council of State and Territorial Epidemiologists to develop a standard case definition for deaths due to measles, so states and the federal government classify deaths the same way.

Children and teens are the largest group

Children and teenagers aged 5 to 19 are the largest group affected, at 1,856 cases, or 42 percent of the total, CDC data showed. Adults aged 20 and older account for 1,787 cases, or 41 percent.

Measles was declared eliminated in the United States in 2000, the CDC says. Coverage with the measles, mumps and rubella vaccine among kindergartners has fallen from 95.2 percent in the 2019 to 2020 school year to 92.4 percent in the 2025 to 2026 school year, leaving about 280,000 kindergartners at risk, according to the CDC. The agency says two doses of the vaccine are 97 percent effective at preventing measles, and one dose is 93 percent effective.

The CDC notes that the 2026 case counts are preliminary and can change. State and local health departments lead measles investigations in their areas and hold the most up to date local information.