Pennsylvania has reported four measles-related deaths in 2023 as the outbreak spreads to 38 counties, highlighting concerns over vaccine coverage and a surge in US cases, the worst since 1991.
Pennsylvania has now recorded four measles-related deaths this year, according to state and federal health officials, as the outbreak continues to spread across the commonwealth and raise concern nationally.
The latest fatality involved an 18-year-old from Mifflin County who died from acute disseminated encephalomyelitis, a rare and serious brain inflammation that can follow measles infection, the Associated Press reported. That death came after the death of a 40-year-old woman in Jefferson County and two infant deaths in Lancaster County, neither of whom was old enough to receive the vaccine.
State health officials said the outbreak has reached 693 confirmed cases across 38 counties, with the Pennsylvania Department of Health warning that daily totals continue to change as new information comes in. AP reported that about 100 new cases were added in the past week alone, underscoring how quickly the virus is still moving through unvaccinated communities.
The outbreak has unfolded as the wider US experiences its worst measles year since 1991, according to the CDC, which says recent case counts are preliminary and still under review. The agency has reported 49 outbreaks in 2025, with most cases linked to outbreaks and the vast majority occurring in people who were unvaccinated or whose vaccination status was unknown. The CDC also says the MMR vaccine is highly effective and that community protection generally depends on about 95% coverage, while US kindergarten vaccination rates have fallen to 92.4% for the 2025-26 school year.
Health officials in Pennsylvania have repeatedly urged parents and caregivers to make sure children are protected with the measles, mumps and rubella vaccine, which is usually given around the first birthday. They say the disease can spread rapidly once it reaches pockets of low vaccination coverage, turning what should be a preventable infection into a broader public health emergency.
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