Pennsylvania health officials announced 693 confirmed measles cases across 38 counties, bringing the total close to 700 infections this year. The outbreak, which began in late April in the Lancaster and Lebanon counties region, has now spread statewide and ranks as the largest in the United States.

Four measles-associated deaths have been reported in the state, all involving unvaccinated individuals. The most recent confirmations include deaths in Jefferson and Mifflin counties, with earlier fatalities linked to Lancaster County. This marks the highest number of measles deaths in any state in decades.

State data shows 133 hospitalizations tied to the illness. The vast majority of cases have occurred among unvaccinated people, with only four infections reported in individuals who were fully vaccinated for their age, representing less than 1 percent of the total.

Pennsylvania Secretary of Health Dr. Debra Bogen stated that vaccination remains the best protection, noting the MMR vaccine is 97 percent effective after two doses. Health officials have conducted pop-up clinics and contact tracing efforts to boost immunization rates in affected communities.

The outbreak has primarily impacted areas with clusters of vaccine hesitancy, including certain religious and cultural groups that have historically maintained lower vaccination coverage. Officials continue to urge residents to review immunization records and seek shots where needed to limit further spread.

Nationally, the Pennsylvania outbreak contributes to elevated measles activity across multiple states. The Centers for Disease Control and Prevention recommends two doses of the MMR vaccine for children and catch-up vaccinations for adults lacking immunity.