NEW YORK (AP) — Measles in the U.S. has climbed to its highest level in 25 years, closing in on 700 cases this year in a resurgence largely attributed to misinformation that is turning parents against vaccines.

“This is alarming,” said Dr. William Schaffner, a Vanderbilt University vaccine expert. Not only is measles dangerous in itself, but its return could mean other vaccine-preventable diseases seemingly consigned to the past may be coming back as well, he said.

The Centers for Disease Control and Prevention said 695 cases had been reported in 22 states this year as of Wednesday afternoon. That was up from 626 reported Monday and makes this the nation’s worst year for measles since 1994, with eight months still to go in 2019. There were 963 cases in 1994.

Roughly three-quarters of this year’s illnesses in the U.S. have been in New York state, mainly in two ultra-Orthodox Jewish communities in Brooklyn and suburban Rockland County. Most of those cases have been in unvaccinated people.

The number of cases is likely to go even higher. Measles is highly contagious and can spread through the air when someone coughs or sneezes.

The CDC recommends the vaccine for everyone over a year old, except for people who had the disease as children. Those who have had measles are immune.

The vaccine, which became available in the 1960s, is considered safe and highly effective, and because of it, measles was declared all but eliminated in the U.S. in 2000.