Most adults and parents have read or heard false claims about measles and the measles vaccine, leaving many unsure of what to believe, a poll by the nonprofit organization KFF showed on Wednesday. The health policy nonprofit polled Americans on whether they had been exposed to three circulating false or misleading statements about measles.

Parents who believe, or lean toward believing, false claims about the measles vaccine say they delayed or skipped some vaccines for their children.

Americans are increasingly being exposed to false claims about measles and vaccines, according to a new KFF poll. It found 33 percent of respondents had “heard” or “read” the false claim that “getting the measles vaccine is more dangerous than becoming infected with measles.