By Islam El-Sakka
Lancaster County, home to the largest Amish population in the U.S., has become the epicenter of the nation's worst measles outbreak in 35 years, with over 1,350 cases reported in Pennsylvania this year, more than a third in Lancaster County alone.
Low vaccination rates in Plain communities
Vaccination rates have long been low among Amish and conservative Mennonite groups, known as Plain communities, due more to cultural habit than religious doctrine. Experts say there is no theological opposition to immunization, but many avoid vaccines because "we never did before, and we came through all right."
Outbreak extends beyond isolated groups
Although Plain communities limit technology and outside interaction, they engage with the general public at farmers markets and medical offices, allowing the virus to spread. Three measles-associated deaths have been recorded in Lancaster County and two elsewhere in the state.
National vaccination decline fuels spread
U.S. kindergarten MMR vaccination rates fell to 92.4% in 2025-26, down from 95.2% in 2019-20, below the 95% threshold needed to prevent outbreaks. Pennsylvania's rate dropped to 93.2%, and every central Pennsylvania county has seen declines since 2020.
COVID-19 pandemic deepened vaccine hesitancy
Doctors report increased distrust and conspiracy theories following COVID-19 vaccines, affecting both Plain and general populations. This hesitancy has contributed to the current outbreak.
Some attitudes shifting toward vaccination
Public health officials are promoting vaccine safety, echoing the successful 1991 response. Clinics report more success with vaccine days, and experts emphasize that vaccination protects the broader community.
