Pennsylvania’s measles outbreak has surpassed 903 confirmed cases across 39 counties as of late September 2026, driven by community transmission in at least 11 counties and resulting in 176 hospitalizations and four deaths, according to state health department data.
Lancaster County Leads Statewide Case Counts as Outbreak Widens
The resurgence continues to worsen across the Commonwealth, marking the most severe measles spread in decades. State health records list 903 positive infections distributed across 39 of the state’s 67 counties, with a cumulative total of 176 patients requiring hospital admission.
Southeastern Pennsylvania remains the epicenter of the surge. Lancaster County records the highest burden with 363 confirmed infections. Mifflin County follows with 106 cases, while Chester County registers 83. State health officials note that at least 11 counties show active community transmission, meaning the virus spreads locally among populations without any documented travel history or identifiable source.
Infant Infections and Fatalities Highlight Clinical Severity
The outbreak has brought rare and dangerous complications, including congenital measles infections in at least six babies born in Pennsylvania, with two so sick they had to be admitted to intensive care.
The Pennsylvania Department of Health confirmed four measles-associated deaths. The fatalities include two unvaccinated adults: an 18-year-old and a 40-year-old. The other two deaths were among infants who were too young to have received the measles, mumps, rubella (MMR) vaccine. The majority of statewide cases occur among those between ages 25 and 49, followed by those between ages 18 and 24.
Pennsylvania reported four measles-related deaths among unvaccinated residents earlier this month, sparking a disagreement between Governor Josh Shapiro and US Health Secretary Robert F. Kennedy Jr. over how many of the fatalities were directly caused by the virus. Soon after, the Centers for Disease Control and Prevention said it was reviewing how it classifies measles-related deaths. The CDC’s website now lists one verified measles death but did not confirm where the death had occurred.
State Administration of MMR Doses and Public Response
To combat transmission, the Pennsylvania Department of Health says it is proactively working with residents, community organizations, and health care providers to combat the measles outbreak in the Commonwealth through access to fact-based information and access to the MMR vaccine. State health officials have administered more than 5,300 MMR vaccinations at 173 pop-up vaccination clinics in the affected communities since the outbreak began in late April. 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, with DOH data showing staff have administered more than 8,300 doses of the MMR vaccine so far this year.
Provider data reveals a substantial surge in public demand. While healthcare providers across the state typically administer approximately 25,000 doses of the MMR vaccine in a typical month, they delivered more than 49,000 MMR vaccines across the Commonwealth in August 2026. Over the first three weeks of September 2026, more than 38,000 doses have been administered.
Medical Guidance on Exposure, Quarantine, and National Totals
Health authorities emphasize that vaccination offers reliable protection, noting that the measles, mumps and rubella vaccine is a routine childhood immunization that provides 97% protection after two doses. State figures show that fewer than 1% of cases—four in total—are among those who are fully vaccinated with the MMR vaccine.
Nationwide, measles cases have surpassed 3,600 so far in 2026, with cases confirmed in 45 states and Washington, D.C., according to the Centers for Disease Control and Prevention. As of September 24, 2026, 3,659 confirmed measles cases were reported in the United States in 2026. Among these, 3,642 measles cases were reported by 47 jurisdictions: Alabama, Alaska, Arizona, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York City, New York State, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming. A total of 17 measles cases were reported among international visitors to the United States. There have been 40 new outbreaks reported in 2026, and 95% of confirmed cases (3,478 of 3,659) are outbreak-associated (2,094 from outbreaks starting in 2026 and 1,384 from outbreaks that started in 2025). For the full year of 2025, a total of 2,289 confirmed measles cases were reported in the United States across 45 jurisdictions.
