Pennsylvania confirms a fourth measles death, an unvaccinated 18-year-old, as the US records its first four measles-related deaths in a year since 1992 amid the worst outbreak in decades.
Pennsylvania health officials confirmed on Tuesday a fourth measles-associated death in the state, an unvaccinated 18-year-old from Mifflin County, pushing the national toll to a level not seen in more than three decades.
The Mifflin County coroner, Andrea L. Alcalde, determined the cause of death to be acute disseminated encephalomyelitis (ADEM), a rare and severe neurological complication of measles. The condition is a rapidly progressing autoimmune disorder in which inflammation triggered by infection strips away the protective covering of nerve cells in the brain and spinal cord. Before widespread measles vaccination, ADEM was commonly associated with the virus.
A death toll unseen since 1992
The state health department also confirmed a third death previously reported by the Jefferson County coroner: an unvaccinated 40-year-old woman. The two earliest deaths in the state occurred in Lancaster County and involved infants — a newborn boy and a six-week-old girl — both too young to be vaccinated.
With the two newly confirmed deaths, the United States has recorded its first four measles-related deaths in a single year since 1992, according to the Pennsylvania Department of Health. Last year, Texas reported two deaths and New Mexico one.
"My thoughts are with the two families who lost loved ones to this highly contagious virus, as Pennsylvania faces the worst measles outbreak in more than three decades," Secretary of Health Dr. Debra Bogen said in a statement. "We remain committed to working with our partners across Pennsylvania to stem this outbreak and prevent more deaths. That means ensuring people have the facts about measles and access to the MMR vaccine — which kept measles outbreaks at bay for decades."
Nearly 700 cases across 38 counties
Pennsylvania has now confirmed 693 measles cases across 38 counties in 2026, including 99 in the past seven days. A total of 133 people have been hospitalized. The state uses a measles-associated death definition modeled on criteria set by the Council of State and Territorial Epidemiologists.
Nationally, the Centers for Disease Control and Prevention is reporting nearly 3,300 measles cases this year — higher than last year's record tally of 2,289, which produced three deaths, and the highest total since 1991, when 9,643 cases were recorded. The US declared measles eliminated in 2000 after blocking domestic transmission for 12 months through high vaccination rates. With coverage slipping well below the 95 percent target, the country is on track to lose that status.
Friction over how deaths are counted
The federal picture is complicated by disputes over reporting. The CDC, now under Health Secretary Robert F. Kennedy Jr., has changed how it counts measles deaths. It previously relied on determinations from state and local health officials; it says it will now report only death records received by the National Center for Health Statistics — a system designed to track long-term mortality trends rather than monitor active outbreaks. The US Department of Health and Human Services did not respond to questions about the change, according to Ars Technica.
Some of the Pennsylvania deaths have already been the subject of public disagreement. Reports have indicated that Kennedy disputed the earlier infant deaths and, according to news accounts, directed the CDC director to exclude reports of two babies' deaths from public communications. Pennsylvania's health department said its determinations were made after thorough investigations.
State officials continue to urge vaccination, noting that the two-dose MMR vaccine provides about 97 percent lifetime protection. People who believe they were exposed and are experiencing symptoms are advised to contact a healthcare provider or call the state hotline at 877-PA-HEALTH.
The two newly confirmed deaths will appear on the state's outbreak dashboard on Wednesday as part of the regular data update.