Like many of the healthcare workers on her staff, Chester County Health Department Director Jeanne Franklin began her career decades ago, when measles presented more often in textbooks than in exam rooms. \u201cMy lead nurse just saw her first measles case the other day \u2013 and she\u2019s been a nurse forever,\u201d noted Franklin.<\/p>\n
But with a dozen residents already hospitalized for measles complications, Chester\u2019s public health workers expect to see more. Since April, when Pennsylvania\u2019s largest measles outbreak in recent history began, the commonwealth has recorded nearly 300 cases<\/a> of the airborne virus, with 61 cases in the past week alone (between January and March, for comparison, the commonwealth recorded only a dozen cases), with 52 of those cases severe enough to require hospitalization.<\/p>\n Public health experts say the true number of measles victims is almost certainly many times higher, since the disease is highly contagious \u2013 nine out of ten people exposed will get sick within three weeks \u2013 and infected family members may not bother with testing. All of the reported cases so far are in unvaccinated individuals, \u201cobviously lending credence to the value of the vaccine,\u201d said Franklin, whose county team has administered more than 350 doses thus far this year, most within the last two weeks.<\/p>\n According to the state Department of Health, the vast majority of measles cases \u2013 161 \u2013 have been reported in Lancaster County, with an additional 37 confirmed in neighboring Chester County as of Friday, Aug. 14. Those cases are \u201cpredominantly within the plain community,\u201d Franklin said, using a term for the traditional Christian groups, such as Amish and Mennonites, that constitute a significant share of those county\u2019s populations.<\/p>\n \u201cThe Pennsylvania Department of Health is working closely with health care providers and local communities to directly combat this measles outbreak,\u201d Neil Ruhland, a press secretary with the state Department of Health, told City & State. The department has responded by vaccinating thousands of residents at pop-up clinics in affected communities, with dozens of additional clinics planned to help curb the outbreak and complement local efforts by counties like Chester, which have their own health departments.<\/p>\n Ruhland added that \u201cthe overall risk remains low if you are fully vaccinated,\u201d pointing out that the standard two-dose MMR (measles, mumps and rubella) vaccine is 97% effective at preventing measles infection. \u201cPennsylvania\u2019s robust baseline immunity is a critical line of defense that will help limit the number of cases compared to regions with lower vaccination coverage,\u201d he noted.<\/p>\n Still, childhood vaccination rates<\/a> have been falling steadily. By the 2025-26 school year, 93% of kindergarteners statewide had received both MMR vaccines, as compared to 97% of 12th-graders. The decline stems from a decades-old anti-vaccine movement fueled by a scientifically debunked 1998 study <\/a>showing an association between the MMR vaccine and autism; more recently, vaccine resistance flared during the COVID-19 pandemic\u2019s culture wars.<\/p>\n And U.S. Health & Human Services Secretary Robert F. Kennedy Jr. and his \u201cMake America Healthy Again\u201d movement ushered in a vaccine-skeptical approach at the federal level last year, including a recent push to dramatically pare back America\u2019s childhood immunization schedule.<\/p>\n Nearly two-thirds of the cases in Pennsylvania\u2019s outbreak involve adults between 18 and 49, which reflects the downward age trend of unvaccinated Americans. In Allentown, Health Bureau Director David Synnamon said the state\u2019s third-largest city recently saw its first measles cases since 2019. The two cases, reported in early August, were not connected to the Lancaster outbreak, he noted, adding: \u201cI think we\u2019re seeing the effects of individuals making decisions to not get vaccinated post-COVID starting to really hammer home.\u201d<\/p>\n