The idea that vaccines are linked to autism risk was born in a study that has been retracted, called "utterly false" by the editor of the journal that published it and refuted many times over by other studies. Nevertheless, the idea continues to seed anxiety among parents. As the number of parents who refuse vaccines has increased, so too have the number of cases of measles. Measles, once declared "eliminated" in the U.S., with 60 cases per year, on average, between 2001 and 2010 has roared back, with 644 cases last year.
In a study published Monday in the Proceedings of the National Academy of Sciences, psychology researchers have found that a more effective way to persuade parents to change their attitudes about vaccinations is not to tell them they're wrong; It's to introduce new facts.
A group of 315 people were split into three groups after their baseline feelings about vaccinations were assessed. One group received a parent's description of what it was like to have a child with measles, warnings about the importance of vaccination, and photos of a child covered with measles and rubella rashes, or a young boy's face horribly swollen by mumps. Another group received information about the absence of a link between vaccines and autism. A third group read about an unrelated scientific topic.
"It was grounded in an old idea from economics, 'expected utility,' in which you weigh the positive and the negative," said Zach Horne, a graduate student in psychology at the University of Illinois at Urbana-Champaign. "What’s going on with anti-vaccination parents, we think, is because they haven’t seen kids with measles and mumps, those consequences aren’t that real to them. And the other consequence, the purported link between vaccination and autism, is."
Horne and colleagues found that trying to tear down the original belief with facts was ineffective. The people who received the latest scientific research about the absence of a link between autism and vaccines changed their attitudes about vaccines about as much as the group that just got some random, unrelated reading material. But those who reviewed the family stories, photos, and a public health warning felt more positive toward vaccines. Those changes were biggest in people that were skeptical of vaccines at the start.
That's a hopeful result, because a depressing study published in the journal Pediatrics last year found that none of these individual pieces of information alone worked against closely held beliefs. Giving parents correct information about vaccine risk, showing photos of children sick with preventable diseases, or providing information about what the diseases individually did not work — and even backfired. Those people who were most concerned about the safety of vaccines were less likely to vaccinate their children when given a dose of correct information.
Brendan Nyhan, an assistant professor of government at Dartmouth College, who did the Pediatrics study, said in an e-mail that the new work was encouraging, but that future research should focus on what the differences were between the two studies that led to such different results. Understanding the conflicting findings might help shape an even more effective education campaign for parents making health care decisions for their children.
This study alone isn't enough to change policy, but it does suggest that perhaps public health officials may not have been thinking enough about how to present information about disease risks and vaccine risks.
Horne said that he began doing Google searches for the images he used in the study to see how easily accessible the information was on the Web site of the Centers for Disease Control and Prevention. It was surprisingly hard to track down, he said, requiring multiple clicks — whereas lists of reasons to refuse vaccines popped up right away.
"I think there are immediate steps we could take; we could make it more easy to access this information and put it on a single page that would hopefully become a top hit when you're Googling," Horne said. "The thing with these parents is they are ultimately interested in the health of their child. They just have incorrect beliefs of where the risks are, and their bet is on the wrong horse."
Making disease risk information more prominent and accessible might be one way to make the correct information more persuasive.