Measles is a disease most Americans had stopped thinking about.
For a generation it was a word from old textbooks, not something you had to worry about on the school run.
That has changed this year, and it has changed fastest in one state.
Pennsylvania health officials confirmed on September 30, 2026 that a fifth person has died from measles in the state's growing outbreak, according to CBS News Philadelphia.
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The person was an unvaccinated resident of Lancaster County.
Four earlier deaths this year were also in people who had not been vaccinated.
The state has now logged 943 confirmed measles cases spread across 39 counties, with 176 people hospitalized.
Lancaster County alone accounts for 381 of those cases.
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Pennsylvania has pulled ahead of every other state
Pennsylvania now has more measles cases than any other state in 2026.
Lancaster County, where most of the deaths have happened, has a childhood vaccination rate of about 85 percent.
Philadelphia, where kindergarten vaccination sits at 94.5 percent, has not reported a single case.
The gap matters because measles spreads easily. Dr. Lawrence Livornese told CBS News Philadelphia how quickly the virus moves through unprotected groups.
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"In a population where people are susceptible, about 9 in every 10 people who are susceptible and are exposed to someone with measles will develop measles," he said.
The virus can hang in the air of a room for up to two hours after an infected person has left.
About one in five people diagnosed in Pennsylvania this year have ended up in the hospital.
The national picture is the worst in 35 years
The country is on track for its worst measles year since 1991.
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The CDC reports 3,887 confirmed cases in the United States so far in 2026, spread across 47 jurisdictions.
Vaccination status tells almost the whole story.
About 95 percent of this year's US cases are in people who are unvaccinated or whose status is unknown.
Only 3 percent are in people who had both recommended doses of the MMR vaccine.
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Children and teenagers are the hardest hit, and the climb in cases comes as a record 4.2% of US kindergartners now hold vaccine exemptions.
What the MMR vaccine actually does
The measles, mumps and rubella shot, usually called MMR, is given in two doses in childhood.
Two documented doses give about 97 percent lifetime protection against measles, according to Pennsylvania health officials.
Catch-up shots are available for older children and adults who were never fully vaccinated.
If you are not sure whether you had both doses, your doctor can check your records or run a simple blood test.
Anyone with a fever and a rash, especially after contact with a known case, should call their doctor before walking into a waiting room.
Pennsylvania has pushed hard on vaccination since the outbreak began in late April.
More than 53,000 MMR doses were given across the state in September, more than double the usual monthly pace.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.