2 new measles cases reported in Chester County as regional Pennsylvania outbreak grows

Two new measles cases have been reported in Chester County, Pennsylvania, as part of a regional outbreak affecting multiple counties with 77 cases since late April. Declining vaccination rates are contributing to increased vulnerability, with Pennsylvania recording 89 cases in 2026 compared to 16 in 2025 and 6 in 2024. The Chester County Health Department is implementing contact tracing and quarantine protocols.