Measles in Pennsylvania: what to know

The Pennsylvania Department of Health has confirmed 12 measles cases so far this year, all among unvaccinated residents in Lancaster, Montgomery and Chester counties. Public health departments are beginning targeted campaigns as vaccination rates have declined and national cases have risen.

The Pennsylvania Department of Health has reported 12 measles cases in the first two months of the year, concentrated in Lancaster, Montgomery and Chester counties. All reported cases were among unvaccinated residents, according to the department. This count is larger than the six cases reported in 2024 and could put the state on pace to exceed last year’s total of 16. Declining vaccination rates and a national rise in measles cases have made the topic a focus for public health officials. What is known: - The Department of Health confirmed 12 cases in the first two months, all in Lancaster, Montgomery and Chester counties. - State officials say all reported infections were among unvaccinated residents. - Pennsylvania had six reported cases in 2024; the current pace could surpass 2024 and last year’s statewide total of 16. - More than half of Pennsylvania counties do not meet the herd immunity threshold for measles, and Allegheny County has not reported a case since 2019. Summary: Declining vaccination rates are cited as a factor behind rising measles counts in Pennsylvania and nationally, which officials say could affect the country’s long-standing elimination status. Public health departments in the state are starting targeted outreach to address hesitancy. Undetermined at this time.