Chester County has more measles cases than most entire states in the country

In late June, Chester County reported two cases of measles, as an outbreak in bordering Lancaster County crossed into the farmlands that blend into the suburban sprawl of Philadelphia’s collar communities.

Case numbers grew tenfold in July, and by late August, three dozen people had gotten sick up and down the county’s western border.

The latest numbers now show 83 measles cases in Chester County, more than most entire states have seen all year, making it a locus in Pennsylvania’s largest measles outbreak in more than three decades.

Chester is the first county in the Philadelphia region to grapple with wide circulation of a highly contagious virus that could spread like wildfire if it reaches other under-vaccinated communities, especially densely populated ones closer to the city.

As cases rise in Chester County, public health officials are ramping up educational outreach, scheduling pop-up clinics, and even bringing doses of the vaccine to people’s homes, all in an effort to contain known hot spots in the outbreak.

At Chester County’s schools, homecoming parades, and grocery stores, many families say they are aware of the outbreak, but are not deeply concerned. Those who are vaccinated worry more that their social and school lives may be disrupted, as they were during the COVID-19 pandemic, if the virus continues to spread.

Anne Nemeth, who lives in Paradise in Lancaster County, feels only a little worried, given that her two sons are vaccinated.

At a time of declining vaccination rates, she isn’t sure whether some of her closest neighbors, who the family regularly gets together with, are vaccinated.

They are Amish, and she has read that many of the people getting sick in her area were part of the Plain community. Two Amish infants in Lancaster County died in August after contracting measles in the state’s first deaths linked to the outbreak.

“I’m hoping they would tell us if they were sick,” she said. “It’s a lot of trust.”

Pennsylvania has reported five deaths associated with measles. A 20-year-old Amish woman who died lived just over the Chester border in Lancaster County. She wanted the vaccine after her parents and eight siblings got sick, but couldn’t get it because she was being treated for leukemia.

Close to 1,000 people statewide have been sickened by the virus, marking one of the most robust outbreaks the United States has seen in years. And experts say the cases that have been reported are likely an undercount, as many people do not seek medical care for their symptoms and some have been reluctant to speak with the health department.

“Public health is now in a race with the disease,” said Dale Weiser, the clinical services supervisor for Chester County’s health department. “It’s going to either burn through all the susceptible people, or we’re going to make fewer people susceptible through vaccination. That’s the only way it ends.”

Measles is so contagious that nine out of 10 unvaccinated individuals who come in contact with the disease will get sick.

That’s how a county like Chester, with one of the highest vaccination rates in the state, has also come to log the third-most cases in the outbreak.

Chester County’s kindergarten measles vaccination rate falls just below the 95% threshold that scientists say is necessary to keep the virus from spreading widely. Kindergarten vaccination offers a view into a community’s protection because the vaccines are required for school attendance.

But the county — like the rest of the Philadelphia region — is pockmarked with areas where vaccination has dropped well below the so-called herd immunity threshold, leaving families vulnerable to severe illness.

In eastern Chester County, for instance, five elementary schools in West Chester had kindergarten measles vaccination rates below 95% — one of the vulnerable areas in the region identified by an Inquirer analysis of 2025-26 school-level data.

Farther east, Chester City in Delaware County, and neighborhoods in West and North Philadelphia have also similarly seen measles vaccination rates drop below so-called herd immunity.

In Chester County, the health department seeks to limit the virus from spreading from west to east across the county, where it would reach more densely populated communities, said Jeanne Franklin, Chester County’s health director.

“If it finds that pocket of unvaccinated individuals, it’s going to popcorn until it finds no one left,” Franklin said.

The health department began reaching out to hospitals and schools months before Chester County reported its first cases, because public health leaders knew it was likely only a matter of time before the virus spread from Lancaster County, Franklin said.

Hospitals were asked to develop a measles screening protocol, if they didn’t have it already, so that early symptoms, such as fever, cough, and runny nose, wouldn’t be dismissed as seasonal illnesses.

Schools were urged to start tracking vaccine status among staff. When a school identifies a measles case, the county requires any student or staff member who is unvaccinated or does not have proof of vaccination to stay home for 21 days, Franklin said. Since many adults don’t have their vaccination records handy, that could create a major staffing disruption.

As case counts in Chester County grow, pop-up vaccine clinics have been scheduled across the county.

The health department has administered more than 500 doses of the measles, mumps, and rubella (MMR) vaccine so far this year, most of them since the outbreak began in April.

The health department’s nurses will bring doses of the vaccine to homes and farms of residents who don’t travel. Vaccines are also available at the county’s health clinics.

Many of the parents lined up along Atglen’s Main Street last week for the local school district’s homecoming parade said they did not feel a reason to be deeply concerned about the outbreak because their families are vaccinated.

“I guess I have the same level of concern as I have for all sickness with kids in public schools,” said Sandi Wrigley, a Cochranville mother whose children, ages 9 and 11, are vaccinated. “If we take the time to worry about that, it’ll be an endless worry.”

Until recently, measles was considered eradicated in the United States, and despite declining vaccination rates, most families are still choosing to vaccinate their children.

Some were angry that measles is even a conversation.

Michael Lavender, from Parkesburg, said vaccinating his 12-year-old daughter was an “easy decision.”

“I really feel like there should be no reason to even talk about it,” he said.

On the other side of the county, families lined up inside the Great Valley Middle School gymnasium in Malvern for flu and COVID-19 vaccines.

Kevin Wrabley, of Malvern, doesn’t worry about his 11-year-old son contracting measles because he is vaccinated. But he does worry about other children and adults who aren’t able to get vaccinated.

“It’s discouraging, things we thought were safely behind us are coming back,” he said.

In Chester County, public health educators have the task of trying to untangle the myriad reasons people are opting out of a vaccination. Many have little to do with science: Two doses of the measles vaccine provide 97% protection — better than most vaccines.

The MMR vaccine is among those long required to attend school in Pennsylvania and every other state. But families here have increasingly been deciding against vaccination for religious and philosophical reasons, as state law permits, often by simply printing and signing a form noting their objection.

Some fluctuations in kindergarten vaccination rates are typical from year to year, but the rise of anti-vaccine rhetoric in federal leadership and a growing distrust in public health authorities has exacerbated fears about vaccination.

On measles awareness flyers posted on social media and in public spaces, Chester County advertises its public health hotline, where people can call to talk to a nurse. Weiser and her colleagues work to dispel worries from callers over misinformation that the vaccine contains tracking chips, heavy metals, and can cause people to become sterile.

Some call back multiple times, with new questions. Weiser answers them all, without judgment and without pushing people to get vaccinated.

“We have a way to prevent this,” Weiser said. “There is no reason that any child, adolescent or adult in this country should be suffering with measles.”

Standard public health messaging — get vaccinated to protect yourself and your family — may not resonate in the area’s rural farming communities that overlap with Lancaster County.

The area has a large concentration of Amish and Mennonite families who are not necessarily opposed to vaccines, but have gone without most traditional medicine for generations.

Anabaptist religions emphasize self-sacrifice for the betterment of others, said Kevin Ressler, CEO of Alliance for Health Equity, a healthcare nonprofit in Chester County.

Instead of vaccinating, families may isolate themselves at the earliest signs of illness to keep anyone else from getting sick, said Ressler, who is Mennonite and has served as a pastor.

» READ MORE: Inside Pa.’s measles outbreak: A family rides out the virus, doctors treat severely ill children

Outside New Holland, Gina King self-quarantined when she and her eight children got sick with measles in June. King was vaccinated, but she and her husband chose not to vaccinate the children.

Her 14-year-old son was briefly hospitalized for breathing difficulty, but he and his siblings all recovered. King, who spoke with The Inquirer in July, later drafted a tip sheet for other families in her Plain community based on their experience, such as stocking up on groceries to avoid going out in the community while contagious.

“If you made the choice to not vaccinate, you knew there was a risk of getting sick,” King wrote. “We should care about others enough to be willing to make some sacrifices to protect vulnerable people.”

Ressler thinks public health messaging may need to be more direct: You are hurting other people by not getting vaccinated.

Measles symptoms may not develop for days or even weeks after exposure, meaning many more people could be exposed before a family decides to quarantine.

Public health nurses say they have had the most success with face-to-face conversations, at people’s homes.

Over the last 15 years, Union Community Care, a public health nonprofit in Lancaster County, has developed a route for its mobile clinic with stops at homes, farms, and churches through Lancaster and western Chester Counties.

The program’s nurse practitioner diagnoses earaches and eye infections, gives general physicals, and can administer vaccines.

The program, called Plain Healthy, depends on hard-earned trust that the nurse will come every 10 days for anyone who needs help. It has spread by word of mouth, adding several more stops in Chester County since the outbreak began, said Alisa Jones, CEO of Union Community Care.

“The most important thing is it is community led,” Jones said. “We are invited to these homes and farms. We do not invite ourselves.”

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