Pennsylvania's Measles Outbreak Is Now the Nation's Largest: Here's What's Driving It

Pennsylvania Measles Outbreak Met With Defiance and a Rush to Vaccinate

Children played softball on a postcard-beautiful day. Business owners sold homemade doughnuts and fresh apple cider.

Pennsylvania's Measles Outbreak Is Now the Nation's Largest: Here's What's Driving It

Pennsylvania's measles outbreak is now the nation's largest, but the CDC's official death count stays at zero. Here's the dispute behind the numbers.

Pennsylvania records four measles-associated deaths in four weeks, the most in a single U.S. state since 1992

Four measles deaths in four weeks have made Pennsylvania the largest active outbreak in the U.S. — and a stress test for what happens when a country's herd immunity quietly collapses.