Measles cases on the rise in Pennsylvania
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Measles cases are surging in Pennsylvania and on track to eclipse last year's total.
Why it matters: Falling vaccination rates are raising alarms that one of the world's most contagious viruses could make a comeback and spread rapidly in densely populated cities like Philly.
State of play: Pennsylvania had 12 confirmed measles cases as of Wednesday — in Lancaster (8 cases), Montgomery (3) and Chester (1) counties, per state health officials.
- All those cases were among unvaccinated people.
- Last year, Pennsylvania recorded 16 cases. In 2024, there were six.
Plus: Two more cases involved out-of-state residents, including one who visited Montgomery County and the other Chester County.
Zoom in: Philly is under a measles health advisory.
- The advisory noted that a large number of travelers are poised to come to Philly for the World Cup and other big events throughout the year.
- While there have been no confirmed measles cases in the city proper so far in 2026, Philly health officials have warned of possible exposure at the city's airport this year.
Between the lines: More than half of Pennsylvania's counties, including Philly, don't meet the herd immunity threshold for measles.
Flashback: Last year, U.S. measles cases topped 2,000 for the first time in over 30 years, per CDC data.
How it works: Measles is highly contagious, spreads easily through the air, and can linger indoors for hours, per the CDC.
- Infection can raise the risk of pneumonia or inflammation of the brain or lungs, particularly in young children.
- Symptoms include high fever, rash, cough and pink eye.
- Plus: Parents who want to protect their newborns have few options as infants typically aren't vaccinated until they're a year old.
State of play: Getting two doses of the MMR or MMRV shot is safe and 97% effective at preventing infections, per the CDC.