Two die in Pennsylvania measles outbreak, first US deaths this year

Two people in Pennsylvania have died from measles, marking the first measles-related deaths in the United States this year. Health officials confirmed that neither of the deceased had been vaccinated against the disease. The deaths are also the first from measles in Pennsylvania in 35 years.

The Pennsylvania Department of Health reports an ongoing outbreak affecting nearly 400 people across 28 counties. The state has responded by updating its vaccination guidance, recommending that children receive their measles-mumps-rubella (MMR) vaccine earlier than usual — as young as nine months — and that adults unsure of their vaccination history consider a booster dose.

Matt Ferrari, a professor of biology and director of the Center for Infectious Disease Dynamics at Penn State, said the resurgence has a simple cause: falling vaccination rates. "As soon as the number of unvaccinated people rises high enough, it's like putting fuel on a fire," he said. "Eventually a match is going to cause a large blaze."

Measles is a severe illness. About 20% of infections require hospitalization, and between 1 in 1,000 and 1 in 3,000 cases prove fatal. Complications can include brain swelling, neurological damage, and pneumonia. The virus attacks immune cells, leaving survivors more vulnerable to other infections for weeks or months.

Nationally, the US has recorded over 2,800 measles cases in 2026 alone, following roughly 2,000 the previous year — more than ten times the annual totals seen in recent decades. Measles had been effectively eliminated in the US, with only occasional cases linked to international travel. Ferrari noted that clusters of unvaccinated individuals, often concentrated in communities with ideological or religious exemptions, allow the virus to spread rapidly once introduced.

He also pointed to a loss of "collective memory" about vaccine-preventable diseases. "We're a victim of our own success," he said. "We haven't maintained the level of vigilance necessary to prevent these outbreaks."

Globally, measles still kills about 250 children under five every day. Ferrari said the current US outbreak shows that risk is returning to communities that had long been protected by public health infrastructure and high vaccination coverage.