An unvaccinated resident of Lancaster County, Pennsylvania, who tested positive for measles has died, state health officials said Wednesday.
This is the fifth measles-associated death in the state so far this year, according to the Pennsylvania Department of Health.
In 2026, Pennsylvania has reported a total of 943 cases across 39 counties. That includes 40 new cases reported since Monday.
Measles outbreak linked to dropping vaccination rates, doctor says
Dr. Lawrence Livornese, an infectious disease specialist at Main Line Health, said the cases reflect decreasing vaccination rates in some areas.
In Philadelphia, where 94.5% of kindergarteners have received the MMR vaccination, which protects against measles, no cases of the disease have been reported. In Lancaster County, the vaccination rate is 85%. That county leads the state with 381 cases of measles in 2026.
“In a population where people are susceptible, about 9 in every 10 people who are susceptible and are exposed to someone with measles will develop measles,” Livornese said.
Pennsylvania now leads the nation with the highest number of measles cases so far this year.
“It’s not the kind of thing you want to be No. 1 in, that’s for sure,” Livornese said.
Livornese said hospitals are taking precautions, including educating front-line workers about the early symptoms of measles, which can be flu-like.
Measles vaccine
The measles-mumps-rubella, or MMR, vaccine is safe and remains the best way to protect against measles, health officials say. The measles outbreak has prompted a growing number of people to get vaccinated.
State healthcare centers have administered more than 5,500 MMR vaccinations since April in communities affected by the outbreak, and nurses have given more than 8,500 doses of the vaccine at pop-up clinics across Pennsylvania.
More from CBS News