Good overview on why this problem is persisting. From Mother Jones:
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Study: You Can't Change an Anti-Vaxxer's Mind
A new study examined multiple strategies for communicating about the safety and importance of vaccines. None of them worked.
—By
Chris Mooney
| Mon Mar. 3, 2014
Vaccine denial is dangerous. We know this for many reasons, but just consider one of them: In California in 2010, 10 children died in a whooping cough outbreak that was
later linked, in part, to the presence of 39 separate clusters of unvaccinated children in the state. It's that simple: When
too many children go unvaccinated, vaccine-preventable diseases spread more easily, and sometimes children die. Nonetheless, as scientifically unfounded fears about childhood vaccines causing autism have proliferated over the past decade or more, a minority of parents are
turning to "personal belief exemptions," so-called "
alternative vaccine schedules," and other ways to dodge or delay vaccinating their kids.
So as a rational person, you might think it would be of the utmost importance to try to talk some sense into these people. But there's a problem: According to a
major new study in the journal Pediatrics, trying to do so may actually make the problem worse. The paper tested the effectiveness of four separate pro-vaccine messages, three of which were based very closely on how the Centers for Disease Control and Prevention (CDC) itself talks about vaccines. The results can only be called grim: Not a single one of the messages was successful when it came to increasing parents' professed intent to vaccinate their children. And in several cases the messages actually backfired, either increasing the ill-founded belief that vaccines cause autism or even, in one case, apparently
reducing parents' intent to vaccinate.
The study, by political scientist Brendan Nyhan of Dartmouth College* and three colleagues, adds to a large body of frustrating research on how hard it is to correct false information and get people to accept indisputable facts. Nyhan and one of his coauthors, Jason Reifler of the University of Exeter in the United Kingdom, are actually the coauthors of a
much discussed previous study showing that when politically conservative test subjects read a fake newspaper article containing a quotation of George W. Bush asserting that Iraq had weapons of mass destruction, followed by a factual correction stating that this was not actually true, they believed Bush's falsehood more strongly afterwards—an outcome that Nyhan and Reifler dubbed a "backfire effect."
Unfortunately, the vaccine issue is prime terrain for such
biased and motivated reasoning;
recent research even suggests that a conspiratorial, paranoid mindset prevails among some vaccine rejectionists. To try to figure out how to persuade them, in the new study researchers surveyed a representative sample of 1,759 Americans with at least one child living in their home. A first phase of the study determined their beliefs about vaccines; then, in a follow-up, respondents were asked to consider one of four messages (or a control message) about vaccine effectiveness and the importance of kids getting the MMR (measles, mumps, rubella) vaccine.
The first message, dubbed "Autism correction," was a factual, science-heavy correction of false claims that the MMR vaccine causes autism, assuring parents that the vaccine is "safe and effective" and citing multiple studies that disprove claims of an autism link. The second message, dubbed "Disease risks," simply listed the many risks of contracting the measles, the mumps, or rubella, describing the nasty complications that can come with these diseases. The third message, dubbed "Disease narrative," told a true story about a 10-month-old whose temperature shot up to a terrifying 106 degrees after he contracted measles from another child in a pediatrician's waiting room.
All three of these messages are closely based on messages (
here,
here, and
here) that appear on the CDC website. And then there was a final message that was not directly based on CDC communications, dubbed "Disease images." In this case, as a way of emphasizing the importance of vaccines, test subjects were asked to examine three fairly disturbing images of children afflicted with measles, mumps, and rubella.
The results showed that by far, the least successful messages were "Disease narrative" and "Disease images." Hearing the frightening narrative actually increased respondents' likelihood of thinking that getting the MMR vaccine will cause serious side effects, from 7.7 percent to 13.8 percent. Similarly, looking at the disturbing images increased test subjects' belief that vaccines cause autism. In other words, both of these messages backfired.
Why did that happen? Dartmouth's Nyhan isn't sure, but he comments that "if people read about or see sick children, it may be easier to imagine other kinds of health risks to children, including possibly side effects of vaccines that are actually quite rare." (When it comes to side effects, Nyhan is referring not to autism but to the
small minority of cases in which vaccines cause adverse reactions.)
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