A sharp increase in measles cases across Pennsylvania raises concerns over vaccination coverage and community immunity as the outbreak spreads to multiple counties and affects children returning to school.
Pennsylvania’s measles outbreak has accelerated sharply, with state health officials confirming 89 new cases in the past week and bringing the 2026 total to 379. That makes Pennsylvania the state with the third-highest measles tally in the country this year, behind Utah and South Carolina, according to the US Centres for Disease Control and Prevention.
Lancaster County remains the epicentre, with 181 cases, while Chester County has recorded 41. Cases have also risen in central Pennsylvania, including 25 in Mifflin County and 13 in Centre County. State officials said the outbreak has now spread across more than two dozen counties, and they warned that people may have been exposed at a soccer camp at Millersville University on August 4 and 5 and at a Whole Foods store in Lancaster on August 12.
The scale of the outbreak is striking compared with last year, when Pennsylvania reported just 16 measles cases. Health authorities say none of this year’s patients had been fully vaccinated. In August alone, officials have confirmed nearly 200 new infections, and they believe the real total may be higher because some residents have not cooperated with contact tracers trying to track the spread.
The outbreak is unfolding as children return to classrooms. About 93% of Pennsylvania kindergarten pupils were vaccinated against measles, mumps and rubella in the 2025-26 school year, just short of the 95% level needed for herd immunity. Axios reported that the state’s kindergarten exemption rate was 6%, above the national average, and that Lancaster County has some of the lowest student vaccination rates in Pennsylvania. Public health officials have also warned that pockets of lower coverage leave communities vulnerable even where most children are immunised.
State officials said 70 people, including 22 children, have been hospitalised this year, and doctors have seen serious complications such as pneumonia, brain swelling, dehydration and organ damage. In response, the health department has organised 85 pop-up clinics since April, delivered more than 4,000 vaccinations this year and held briefings for nearly 1,000 school nurses over the summer. Officials are also urging doctors in affected areas to consider vaccinating children as young as six months old.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
