Pennsylvania health officials have reported a fifth measles-associated death this year, as the state continues to experience one of the largest measles outbreaks in the United States.

The Pennsylvania Department of Health said the latest death involved an unvaccinated Lancaster County resident. The state reported 943 confirmed measles cases across 39 counties, along with 176 hospitalizations, as of September 30.

The development comes as the U.S. faces its worst measles year since 1991. Nationally, the CDC had recorded 3,659 confirmed measles cases through September 24, while Pennsylvania officials said more than 53,000 MMR vaccine doses were administered statewide during September as demand for vaccination increased.

A difference remains between Pennsylvania's reporting and the CDC's national count. Pennsylvania classifies the five deaths as measles-associated, while the CDC's federal count had confirmed two measles-related deaths as of September 24, reflecting different approaches to confirming cause of death.

Health officials continue to emphasize MMR vaccination as the main protection against measles, while monitoring the outbreak and providing vaccination clinics in affected communities.