Lancaster County becomes epicenter of worst US measles outbreak in 35 years

US kindergarten MMR vaccination rate fell to 92.4% in 2025-26

Lancaster County, Pa., home to the largest Amish population in the United States, is now the epicenter of the nation’s worst measles outbreak in 35 years. Pennsylvania has the most U.S. cases, with more than 1,350 this year and more than a third of them in Lancaster County alone, according to state health figures. Community leaders say the count is likely a big undercount because many people with measles never see a doctor.

The state has recorded five measles-associated deaths: three in Lancaster County and two in other counties.

The outbreak has hit hardest among the “Plain communities” of Amish and conservative Mennonites, so named for the religious groups’ modest dress and limited use of technology. Vaccination rates and attitudes about vaccines range widely among them, but overall they are less likely to be vaccinated than the general population, due more to culture and habit than doctrine, according to community leaders and scholars.

Measles, officially considered eliminated from the United States since 2000, spreads easily when people who have it breathe, cough or sneeze, or through contaminated surfaces.

“Measles is really the lion king of infectious diseases when it comes to transmission,” said Michael Osterholm, who directs the University of Minnesota’s Center for Infectious Disease Research and Policy. “No one in the United States of America who is susceptible to the measles virus, either having not been vaccinated or not having previously had it, should feel safe from measles. No one.”

The risk grows as vaccination rates decline across the nation. According to the Centers for Disease Control and Prevention, 92.4% of U.S. kindergarteners in 2025-26 received the required MMR shots, down from 95.2% in 2019-20. Pennsylvania’s overall kindergarten MMR vaccination rate fell to 93.2% by last year, below the 95% rate that makes an outbreak extremely unlikely in a community.

“Though Plain communities are an easy and recognizable target, declining childhood vaccination rates in our county are not limited to the Amish,” wrote Berwood Yost, director of the Center for Opinion Research at Franklin & Marshall College in Lancaster, in a recent commentary. “Kindergarten vaccination rates have declined in every central Pennsylvania county since 2020.”

Attitudes toward vaccines in Plain communities have alternately warmed and cooled over the years, most recently cooling in reaction to strict COVID-19 public health measures, according to community leaders and scholars. The measles outbreak is prompting many to accept the shots while reinforcing vaccine skepticism and suspicion in others.

Those who avoid vaccines usually aren’t driven by ideology, community leaders and experts say. “There’s nothing in Amish theology or historic documents that you can find that specifically addresses or is opposed to immunization,” said Steve Nolt, director of the Young Center for Anabaptist and Pietist Studies at Elizabethtown College in Lancaster County.

Allen Hoover, an Old Order Mennonite and former administrator of the Parochial Medical Center in the town of New Holland, said the main reason Plain people skip vaccinations isn’t that they’re against them. “It was simply, ‘Well, we never did before, and we came through all right.’”

During the COVID-19 pandemic, area doctors saw more vaccine hesitancy among patients within and outside Plain communities. “The COVID vaccine just created a lot of distrust, a lot of conspiracy theories,” said Dr. Anne-Marie Derrico, chief medical officer at the nonprofit Union Community Care. “There’s still kind of an overall distrust of vaccines.”

Public officials are now urging vaccination. Lancaster County Commissioner Alice Yoder said officials need to promote the message that the vaccine is safe and effective and encourage people to get it — an approach that succeeded during Pennsylvania’s last measles outbreak in 1991. “There were lines of people in the Plain community that would come and get vaccinated,” she said.

Dr. D. Holmes Morton, who founded the Central Pennsylvania Clinic in Mifflin County, which treats Plain patients with genetic diseases, said the same is happening now. “We are having more success at having vaccine days,” he said.

Dr. Diego Hijano of St. Jude Children’s Research Hospital said getting the shot protects the community as well as the individual. “You will get protected yourself. But in truth, you are actually protecting everyone around you,” he said, calling vaccination “an act of love to your community.”

The outbreak follows ones in 2025 in Mennonite populations in Texas and elsewhere, and most states have recorded cases this year. Although Plain communities avoid participating in many areas of society, they are not isolated — they interact with the general public at farmers markets, doctors’ offices and elsewhere — and their new openness to vaccines, after bearing the brunt of the outbreak, impacts the entire community.