A measles outbreak in Pennsylvania has infected dozens of pregnant women and triggered rare cases of congenital measles, state health officials warned this week, as the nationwide resurgence of the virus expands into the deadliest American outbreak in decades.
The Pennsylvania Department of Health issued an advisory alerting physicians to watch for congenital measles, a condition transmitted in utero that had vanished from American hospitals for generations, CIDRAP reported. According to the advisory, 66 pregnant women in the state have contracted measles this year, and at least six infants have been born with the disease.
Vulnerable infants and adult infections
Pennsylvania has documented 1,286 confirmed measles infections since April, with 109 detected over the past week, CIDRAP reported. Across the United States, confirmed cases have surged past 4,400 this year, nearly double the total from 2025 and the highest level in more than three decades, according to public health figures.
Unlike typical childhood outbreaks, about two-thirds of the patients in Pennsylvania are adults, the vast majority of whom are unvaccinated, CNN reported. The infection has spread heavily within Amish and Plain communities, where vaccine coverage is low and decades without circulating virus left many adults without acquired immunity. Because unvaccinated mothers cannot pass protective antibodies to newborns, infants too young for the measles, mumps, and rubella vaccine face acute danger, Dr. Matthew Ferrari, director of the Center for Infectious Disease Dynamics at Penn State University, told CNN.
The state has recorded six deaths connected to the outbreak, including at least two infants, CIDRAP and CNN reported. Five deaths are formally classified by the state as measles-associated, while a sixth case—involving a 39-year-old woman in Franklin County who suffered a fatal acute cardiac event—remains under review by state investigators.
Clash over federal reporting
The severity of the crisis has triggered a sharp public dispute between Pennsylvania leaders and federal health authorities. On Wednesday, the U.S. Centers for Disease Control and Prevention added a third measles death to its national dashboard but refused to identify the state where it occurred, citing federal privacy statutes, The Guardian reported.
Legal scholars and former public health leaders rejected that explanation. Dorit Reiss, a law professor at UC Law San Francisco, told The Guardian that revealing a patient’s state does not disclose personal identifying details. Debra Houry, a former CDC chief medical officer, noted that Pennsylvania’s deaths were already public knowledge, adding that the federal agency has historically shared such regional figures through notifiable disease tracking networks.
The CDC’s dashboard continues to record only three measles deaths nationwide, despite Pennsylvania confirming five, according to reporting by CNN and The Guardian. Dr. Debra Bogen, Pennsylvania’s health secretary, urged CDC Director Dr. Erica Schwartz in correspondence to include the state’s fatalities on federal trackers, writing that failing to record the deaths hides the true toll of the disease, CNN reported.
Physicians emphasize that women should obtain the MMR vaccine prior to pregnancy, as the immunization cannot be administered during pregnancy due to containing live weakened virus. Unvaccinated pregnant women exposed to measles can receive immunoglobulin treatments within a six-day window, state guidance noted.
A CDC epidemiologist arrived in Pennsylvania this week on an Epi-Aid deployment to evaluate local vaccination initiatives and assess the actual spread of the outbreak. Federal officials have not yet announced when national dashboards will reflect state casualty figures or whether the U.S. will retain its formal measles elimination status next month.
