mind & bodyanalysisThe Conversation (US)2026 · Pennsylvania, USA

What the measles vaccine’s ‘97% effective’ rating means for Pittsburgh parents

the gist

Pennsylvania is experiencing its worst measles outbreak in over three decades, with more than 1,400 confirmed cases and six measles-associated deaths in 2026. Exposure alerts have come from hospitals, grocery stores, restaurants, schools and universities, and each says: check your MMR vaccine status and watch for symptoms for three weeks. Two doses of the MMR vaccine are about 97 percent effective at preventing measles. Measles is extremely contagious, and when vaccination rates fall in a community, outbreaks follow.

so what

The figure means that even among vaccinated people a few can still get sick, so high community vaccination is what protects infants and those who can't be vaccinated.

fun fact

One person with measles can infect most unvaccinated people nearby, and the virus can linger in the air for up to two hours.

The Conversation

Illustrative photo · CDC/NIP/Barbara Rice, Public domain, via Wikimedia Commons