More than 4,400 measles cases confirmed

The Centers for Disease Control and Prevention reported more than 4,410 confirmed measles cases across the US on Friday, with cases in 45 states and Washington, D.C.

Pennsylvania hit hardest by outbreak

Pennsylvania alone has reported at least 1,200 measles cases and six measles-related deaths, according to local health officials.

Most cases among unvaccinated people

About 96 percent of cases are among people who are unvaccinated or whose vaccination status is unknown, according to CDC data.

CDC deploys disease detective to Pennsylvania

Pennsylvania formally requested CDC assistance through the Epi-Aid program. The CDC will send a disease detective to support the state's outbreak response efforts.

“Pennsylvania has formally requested CDC assistance through the Epi-Aid program. In response, CDC will support the state's identified needs and strengthen its response efforts on the ground.”

Vaccination rates have declined since pandemic

During the 2025-26 school year, 92.4 percent of kindergartners received the MMR vaccine, down from 95.2 percent in the 2019-20 school year before COVID-19.

Vaccine effectiveness remains high

The CDC recommends two doses of the MMR vaccine. One dose is 93 percent effective against measles, and two doses are 97 percent effective.

Epidemiologist warns of lost progress

John Brownstein, epidemiologist at Boston Children's Hospital, said deploying federal disease detectives to investigate measles in 2026 is extraordinary for a preventable disease.

“The fact that we're deploying federal disease detectives to investigate measles outbreaks in 2026 is pretty extraordinary. This is a disease we know how to prevent.”

Kennedy attributes outbreak to pandemic gaps

Health Secretary Robert F. Kennedy Jr. said the measles outbreak is occurring because so many people went unvaccinated during the COVID pandemic.

“The measles outbreak is occurring because so many people went unvaccinated during the COVID pandemic.”