Could Philly See Another Measles Outbreak? Lancaster County, the epicenter of the state’s outbreak just 66 miles from Philly, has had 116 this year, while our neighbor, Chester County, has confirmed 21 cases since April. More than 94 percent of Philadelphia kindergarteners were up to date on their measles vaccine during the 2023-2024 school year. “I’m not sure everybody’s even aware there’s a [measles] outbreak,” she says. “Similarly, if you live in an area where measles cases are occurring, I suggest discussing with your healthcare professional about timing of vaccination.”