Measles could become endemic in the United States if routine childhood vaccination rates continue to decline, with up to 51 million illnesses over a 25-year period, according to a new study.

A new study warns that the U.S. could see millions of new measles cases over the next 25 years if vaccination rates continue to fall. The research, published in science journal JAMA, used modeling to forecast the number of measles cases in several scenarios, including vaccination rates holding steady, rising or falling.

Measles, once virtually wiped out in the United States, could become commonplace again if declining vaccination rates continue, a new model shows.