A Jefferson County woman with measles died Saturday, according to local officials. The Jefferson County Coroner’s Office confirmed the county’s first measles-related death in a statement this weekend as Pennsylvania’s statewide measles outbreak continues to explode.

“This is a heartbreaking loss for the family and an unfortunate reminder that measles can be a serious and potentially life-threatening disease,” said Coroner Greg Furlong. “Our thoughts and prayers are with the family during this difficult time.”

The woman, whose identity was not shared by the office, was 40 years old.

According to The Philadelphia Inquirer, the woman had been unvaccinated. Furlong told the paper that the woman developed symptoms of a measles infection after known exposures. According to the paper, he determined she was vulnerable to measles complications due to an underlying respiratory condition.

Measles can lead to severe lung infections, worsen asthma symptoms, and temporarily weaken the immune system, according to the American College of Allergy, Asthma and Immunology.

“Many people associate measles with a childhood illness, but it can lead to severe complications in individuals of any age,” said Jefferson County Chief Deputy Coroner Jason Stiver. “Measles is highly contagious and can result in serious respiratory illness, hospitalization, and in rare cases like this, death.”

The Jefferson County woman is the third person in Pennsylvania to die from complications related to measles this year, according to state officials. Pennsylvania’s Department of Health reported two measles-associated deaths last month in Lancaster County. It was later revealed by the coroner there that both decedents were infants.

Infants are at high risk of severe measles infections because they are too young for the routine measles, mumps and rubella vaccine (MMR), and antibodies passed from their mother begin to wane after birth over a period of months. Pennsylvania health officials have recently recommended that babies six to 11 months get one early dose of the MMR vaccine. Officials still recommend that parents follow up with the recommended two-dose schedule afterward.

The woman in Jefferson County is the state’s first adult death attributed to complications related to measles this year. The news comes as Pennsylvania’s measles outbreak tops 676 cases, leapfrogging South Carolina to become the largest outbreak in the nation.

Cases stretch across 37 of the state’s 67 counties, and 124 people have been hospitalized, according to health department data.

Nearly all cases have been among those who are unvaccinated, according to state data. Four vaccinated individuals have reported measles infections, accounting for 0.5% of cases.

Federal and state health leaders at odds

While Pennsylvania officials count the latest death as the third associated with the measles outbreak, federal officials are calculating them differently. Though data from the Centers for Disease Control and Prevention typically mirrors that at the state level, the agency’s data has not reflected any measles-related deaths so far this year.

In a statement on its website, the CDC said it “does not currently have any death records from 2026 that indicate measles is the underlying cause.”

Pennsylvania’s response to the rapid outbreak has put the state at odds with the CDC and U.S. Health and Human Services Secretary Robert F. Kennedy Jr., whose controversial stance on vaccines was the target of sharp criticism from Gov. Josh Shapiro during a press conference last month.

“His actions and the rhetoric that’s coming from this administration are having a negative impact on communities across America, particularly right here in Pennsylvania,” Shapiro said. “There [are] real-life consequences to spreading misinformation.”

Kennedy, who oversees the CDC, fired back at Shapiro and suggested the measles deaths “may even have been altogether fabricated.”

Both cases were in Lancaster County, the epicenter of the state’s outbreak and home to one of the nation’s largest Amish settlements.

Lancaster County coroner Dr. Stephen Diamantoni later confirmed that baby Ivan Miller died Aug. 14 of a ruptured spleen shortly after his birth. Diamantoni told the Associated Press that the second baby who died was 6-week-old Mary Stoltzfus. He said she was born with a genetic birth defect that left her vulnerable to infection.

Diamantoni said his office did not perform an autopsy on Stoltzfus, and the cause of death was determined by the doctors caring for her.