Pennsylvania's measles death toll climbed to four on Tuesday, Sept. 15, the highest number of U.S. measles deaths in a single year since 1992.
The two newly confirmed deaths were an 18-year-old unvaccinated woman in Mifflin County and a 40-year-old unvaccinated woman in Jefferson County, the state Department of Health announced.
The state has now confirmed 693 cases across 38 counties, with 99 new cases in the past week alone, Patch reported. Chester County, which borders Montgomery County, has recorded 65 cases, including nine new ones in the past week. That puts the outbreak on the doorstep of Whitemarsh, Plymouth and Whitpain townships.
Montgomery County's case count remains at three, with no new cases as of the Sept. 15 report. The Montgomery County Office of Public Health states there are no current cases associated with the outbreak, though the county's page was last updated Sept. 4.
As we reported Sept. 15, Montgomery County's case count had tripled and the state had just recorded its third death. The fourth death came the same day.
What officials are saying
Pennsylvania Secretary of Health Dr. Debra Bogen said in a Sept. 15 statement that the state "faces the worst measles outbreak in more than three decades."
Chester County's public health director, Jeanne Franklin, told ABC News her department has administered 538 MMR doses and launched at-home vaccinations. "We basically just said, 'We've got to do some at-home vaccinations,'" Franklin said. "It's not an everyday type of service … but we're doing it now and that has been a huge success."
More than 99% of Pennsylvania's measles cases have been among unvaccinated people, according to PennLive, citing state health officials. Statewide, 133 people have been hospitalized, according to ABC News.
Chester County ranks third statewide
Chester County's 65 cases trail only Lancaster County at 265 and Mifflin County at 74. The first two measles deaths this year occurred in Lancaster County and were the first measles deaths in Pennsylvania in 35 years.
The Mifflin County coroner determined the 18-year-old's cause of death was acute disseminated encephalomyelitis, or ADEM, a rare neurological complication of measles, Patch reported. Jefferson County Coroner Greg Furlong confirmed the 40-year-old woman died Saturday, Sept. 12.
How Montco residents can protect themselves
Two doses of the MMR vaccine are about 97% effective at preventing measles, according to the Centers for Disease Control and Prevention (CDC). Measles is highly contagious. About 90% of unvaccinated people who have close contact with an infected person will contract the virus.
Montgomery County offers free MMR vaccines for uninsured or underinsured residents at two clinics: Norristown (610-278-5145) and Pottstown (610-970-5040). The county has also posted community vaccination clinics for October 2026 on its website.
Residents vaccinated before 1968 may need a new dose because older vaccines were less effective. Those unsure of their status can ask a health care provider for a measles titer, a blood test that checks for antibodies.
Anyone who suspects exposure and develops symptoms should call their provider or the Montgomery County Office of Public Health at 610-278-5117 before leaving home. The state's toll-free measles hotline is 877-PA-HEALTH (877-724-3258).
