State figures for last school year showed kindergarten measles, mumps and rubella vaccination rates below 95% at five of the district’s 11 elementary schools. Public health experts have long considered that level necessary to help prevent community spread. Penn Wood Elementary reported a rate of 87.5%: 56 of 64 kindergartners had received the vaccine. Five students had philosophical exemptions, while four others were listed as noncompliant but attending.

At Westtown-Thornbury Elementary, the reported rate fell from 100% two years ago to below 92% last year, with seven students claiming religious exemptions. Glen Acres and East Goshen elementary schools also recorded declines and rates below the 95% benchmark.

Superintendent David Christopher said the figures may not reflect current conditions. District nurses contacted families whose children lacked vaccination records, and additional documentation and vaccinations have since been reported, he said. Looking across all grades, Christopher said, every campus now has a vaccination rate above 95%.

Even so, René Najera, public health director at the College of Physicians of Philadelphia, cautioned that high overall coverage does not eliminate risk during an outbreak. “You could have a population with 96% vaccinated, and still have a roaring infection go through,” he said.

The district, which serves about 12,000 students, has not shared school-by-school vaccination data with families or sent a districtwide message highlighting the outbreak, according to the information available. Christopher said the district’s outreach to families is intended to provide information, not pressure them. “We understand that there are a variety of reasons that families may make this decision,” he said.

Health communication researcher Holley Wilkin said schools have a role in sharing information about health threats affecting students and staff. She noted that parents of children who cannot be vaccinated may be especially concerned when schools stay silent.

Other Chester County districts described limited steps. Downingtown Area School District said it had discussed possible quarantines with staff and contacted families whose students lacked current records. Kennett Consolidated School District said it had told families and staff that measles immunization protects the wider community. Of 12 Chester County districts contacted about their preparations, West Chester was the only one to agree to an interview.

A measles case in a school can trigger significant disruption. Chester County health officials say exposed students and staff who cannot show proof of vaccination must remain home for 21 days. Earlier this month, Oxford Area High School closed for a day after a reported measles case so staff vaccination records could be checked.

Christopher said West Chester has set up a secure portal for staff to submit vaccination records, though locating documentation remains a challenge. He said most staff members are vaccinated but could not estimate how many had provided records. The district is weighing how much to invest in outbreak preparations, he said, while recognizing that a lack of readiness could draw criticism.

Pennsylvania allows religious, philosophical and medical exemptions to school immunization requirements. State officials published school-level vaccination data this summer, offering families a closer look at vaccination coverage within their communities. The West Chester figures underscore how districtwide averages can mask lower rates at individual schools as an outbreak approaches.