As the United States faces its worst measles outbreak in a decade, misinformation about the disease and its vaccines is spreading rapidly, according to a new survey by KFF Health News.

As of April 17, the Centers for Disease Control and Prevention (CDC) reported 800 confirmed measles cases across 25 states. The hardest-hit region is West Texas, where two unvaccinated school-aged children have died. An unvaccinated adult also died in New Mexico.

“The most alarming part of the survey is that more people are now hearing and potentially believing these false claims,” said Ashley Kirzinger, associate director of KFF’s Public Opinion and Survey Research Program.

The federal response has drawn criticism, with limited urgency from the Trump administration. Health and Human Services Secretary Robert F. Kennedy Jr. downplayed the outbreak, calling it “not unusual” and failing to promote vaccination in his statements.

The survey highlights a deep partisan divide in awareness. While about two-thirds of Democratic-leaning parents were aware of the outbreak, the same proportion of Republican-leaning parents were not. Among parents who believed at least one false claim, 25% admitted to skipping or delaying vaccines for their children — more than double the rate among parents who rejected misinformation.

Public health experts warn that this rising uncertainty — exacerbated by post-COVID-19 vaccine skepticism — leaves the population increasingly vulnerable to preventable disease outbreaks.

Although measles was declared eliminated in the U.S. in 2000, falling vaccination rates have allowed it to return in alarming numbers, raising concerns about the potential loss of the country’s elimination status.

Measles is a highly contagious viral illness spread through respiratory droplets. It causes high fever, cough, runny nose, and a widespread rash.