Pennsylvania measles outbreak grows to 890 cases with 55 new infections: Officials
At least 173 people have been hospitalized.
The measles outbreak in Pennsylvania is continuing to grow with 55 new cases confirmed since Wednesday, according to an update from the state health department.
Friday's update brings the total number of measles cases so far this year in the state to 890 across 39 counties. At least 173 people have been hospitalized and four measles-associated deaths have been reported.
Fewer than 1% of the state's cases -- four in total -- are among those who are fully vaccinated with the measles, mumps, rubella (MMR) vaccine, data from the Pennsylvania Department of Health (DOH) shows.
The majority of cases are among those between ages 25 and 49, followed by those between ages 18 and 24, according to state health department data.
Lancaster County in southeastern Pennsylvania has recorded the highest number of cases at 359 followed by Mifflin County, in the central part of the state, with 102.
The state health department is asking anyone who believes they were exposed to measles and is experiencing symptoms to contact their health care provider or call the department's toll-free hotline at 877-PA-HEALTH (877-724-3258).
"State health officials have administered more than 5,300 MMR vaccinations at 165 pop-up vaccination clinics in the affected communities since the outbreak began in late April," DOH said in a press release. "Dozens of additional vaccine clinics are scheduled for the upcoming weeks and months, based on community interest and need. Overall, state health center staff have administered more than 7,900 MMR vaccine doses to residents across the Commonwealth in 2026."
The DOH added that health care providers have seen an increase in those interested in receiving the MMR vaccine. Typically, about 25,000 MMR doses are administered every month, it noted. By comparison, more than 49,000 MMR doses were administered in August 2026 and more than 38,000 doses were administered during the first three weeks in September, according to DOH.
"Measles is a nasty virus and highly, highly contagious -- the most contagious virus we know -- and it's so sad that it continues to occur and afflict even a single child in the United States because it's a completely preventable disease," Dr. William Schaffner, professor of preventive medicine at Vanderbilt University Medical Center in Nashville, told ABC News.
Meanwhile, measles cases in the U.S. have surpassed 3,600 so far in 2026, with cases confirmed in 45 states and Washington, D.C., according to the latest data from the Centers for Disease Control and Prevention.
The CDC currently recommends that people receive two doses of the MMR vaccine, the first at ages 12 to 15 months and the second between 4 and 6 years old. One dose is 93% effective in preventing measles infection and two doses are 97% effective, the CDC says.
However, CDC data shows vaccination rates have been lagging in recent years. During the 2025 to 2026 school year, 92.4% of kindergartners received the MMR vaccine, according to data. This is lower than the 95.2% seen in the 2019 to 2020 school year, prior to the COVID-19 pandemic.
"I think it is concerning that there will be more outbreaks, some larger, some smaller, because it's clear from the national data that a proportion of parents are withholding their children from vaccination," Schaffner said. "They have questions. They have concerns. They have hesitancy, and I always say, speak to your child's doctor, a pediatrician, a family doctor, and voice your concerns, express your hesitation, and have that conversation with your doctor."
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