Pennsylvania measles outbreak nears 800 cases as officials report four deaths
Pennsylvania has recorded 792 measles cases this year, the largest U.S. outbreak in 2026, with four deaths linked to the disease and a statewide push for vaccinations.
Pennsylvania health officials said on Monday that the state has recorded 792 measles cases this year, including nearly 100 new infections in the past week. The outbreak, centered in Lancaster County where more than 300 cases have been confirmed, is the largest in the United States for 2026. Chester County has reported 76 cases, while Mifflin County leads the state with 93 cases.
State health data list four measles-associated deaths: two infants in Lancaster County, a 40-year-old woman in Jefferson County and an 18-year-old in Mifflin County. The state defines a measles-associated death as one occurring within 30 days of symptom onset in a person with clinical evidence and a positive laboratory test for measles, without another unrelated cause. Lancaster County’s coroner noted that one infant died from a lacerated spleen, though the baby tested positive for measles, and physicians have warned that the infection can weaken the spleen.
"Incompetence is denying the tragedy of four measles-associated deaths in Pennsylvania," Governor Josh Shapiro wrote on X in response to criticism.
"The deaths were fabricated," Health and Human Services secretary Robert F. Kennedy Jr. initially claimed, later acknowledging that one death was caused by measles.
Federal officials have said Pennsylvania has not yet listed the deaths on the CDC’s measles outbreak dashboard and has not formally requested an Epi-Aid team, a rapid-response resource for health emergencies. Pennsylvania health secretary Debra Bogen said the state is working with CDC staff and is beginning the request for an Epi-Aid team, contingent on the agency’s acknowledgment of the deaths.
In the Philadelphia area, Chester County remains the only county with reported cases from the current outbreak that began in April. Health officials identified two potential exposure events: a measles-positive individual visited the Children’s Hospital of Philadelphia’s neonatal intensive care unit on Sept. 11, and another traveled through multiple terminals at Philadelphia International Airport on Sept. 13. Exposed infants at the hospital were isolated and given antibodies.
Vaccination rates in Pennsylvania have been declining, with many kindergartens in the Philadelphia region falling below the 95 % herd-immunity threshold. The state announced a free measles, mumps and rubella (MMR) clinic at the Bloomsburg Fair from Sept. 26 through Oct. 3 and has conducted 148 pop-up vaccination sites, delivering more than 4,800 MMR doses since April. Provider reports show monthly MMR administrations rose from the typical 25,000 to over 46,000 in August and more than 25,000 in the first two weeks of September.