The Journal of the American Medical Association has found that most of the people who didn’t get vaccinated and then got measles last year had refused those vaccinations, reports Tara Haelle of Forbes:

Even though measles was eliminated from the U.S.—meaning the disease no longer circulated on its own within U.S. borders—16 years ago, outbreaks have continued to result from occasionally imported cases. But the disease can only spread if enough people are not vaccinated against it—and that’s precisely why the U.S. has seen an increase in measles outbreaks. In fact, well over half of people who have caught measles in the past decade and a half were unvaccinated, and most of them had refused the measles vaccine, found a recent study in JAMA.

Read the full article here.