WEST CHESTER, PA — Chester County health officials are preparing for measles infections to spread from neighboring Lancaster County as Pennsylvania’s outbreak approaches 1,000 confirmed cases, increasing pressure on local vaccination, surveillance and contact-tracing efforts.
Pennsylvania had recorded 977 confirmed measles cases across 39 counties as of Oct. 2, according to the state Department of Health. The outbreak has resulted in 195 hospitalizations and five measles-associated deaths.
Chester County had 83 cases, the third-highest county total in Pennsylvania, according to reporting published Oct. 4 by The Guardian. Lancaster County, which shares an extensive border with Chester County, remains the center of the outbreak.
“We have a very long border with Lancaster county, and these types of disease don’t care about borders,” Chester County Health Department Director Jeanne Franklin said in The Guardian article.
Franklin indicated that the county is preparing for transmission to extend beyond the populations where many infections have so far been concentrated.
“It’s going to keep going and find a person who isn’t vaccinated,” Franklin said in the article. “Our goal is to prevent that, but we assume that it may happen.”
The local response includes active disease surveillance, contact tracing, community vaccination efforts and outreach aimed at countering inaccurate information about the measles, mumps and rubella vaccine.
Chester County’s ability to mount that response is aided by its county health department, a structure that exists in only a small number of Pennsylvania counties.
Franklin cited the department’s established relationships with local organizations and its ability to redirect employees when outbreaks emerge as advantages over relying exclusively on state resources.
“We live here, we know it, and we’re working with the communities and the organizations who know us,” Franklin said in The Guardian article.
The statewide outbreak has accelerated in recent weeks. Pennsylvania reported 943 cases on Sept. 30 before the total climbed to 977 two days later, an increase of 34 infections.
State health officials reported that only four of the 977 confirmed cases involved vaccinated people, accounting for less than 1% of infections.
Pennsylvania has expanded vaccination efforts as cases have mounted. State health center personnel have administered more than 5,600 MMR vaccinations through 189 pop-up clinics in affected communities since the outbreak began in late April.
Combined with vaccinations administered at state health centers, Department of Health nurses have provided more than 8,700 MMR doses statewide this year.
Demand has also risen through other health care providers. Pennsylvania typically records about 25,000 MMR vaccinations in a month, compared with more than 49,000 in August and more than 53,000 during September.
Two documented doses of the MMR vaccine provide about 97% protection against measles, according to the Department of Health. People with two documented doses do not need another vaccination.
Measles is highly contagious and spreads through the air when an infected person breathes, coughs or sneezes. The virus can remain infectious in the air and on surfaces for as long as two hours after an infected person leaves an area.
Symptoms typically begin with fever, cough, runny nose and red, watery eyes, followed several days later by a rash beginning on the head and spreading downward. Symptoms can develop seven to 21 days after exposure, and an infected person is typically contagious from four days before through four days after the rash appears.
Nearly 20% of Pennsylvania residents identified with measles during the outbreak have been hospitalized.
Residents who believe they were exposed and develop symptoms should contact a health care provider or the Pennsylvania Department of Health at 877-PA-HEALTH (877-724-3258).
Current state outbreak data are available at https://www.pa.gov/agencies/health/dashboards. Chester County outbreak information is available at https://www.chesco.org/6019/Measles-Outbreak.
For additional reporting on Pennsylvania’s outbreak and the challenges facing local health departments, read The Guardian’s article at https://www.theguardian.com/us-news/2026/oct/04/pennsylvania-health-officials-measles-outbreak.
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