A Shot in the Dark – The Perils of Sharing Vaccine Science

One of Wikipedia’s most interesting articles is simply titled “List of common misconceptions.” The contents range from the invention of baseball (Alexander Cartwright, not Abner Doubleday, first codified the rules) to elephant graveyards (which do not actually exist), covering the kind of “folk knowledge” that might be erroneously relayed in a grade-school classroom. Most of these myths are harmless misunderstandings, but the fact that the article exists at all points to the frustrating difficulty of correcting false information on a societal scale.

Some misconceptions, however, have effects beyond making people sound foolish at cocktail parties. The belief that vaccinations cause autism, thoroughly debunked by the best available science, has led to a decrease in rates of vaccination against preventable diseases in many areas across the United States. This reduction in immunity among the population in turn leads to outbreaks of diseases long thought controlled, such as whooping cough, which killed 10 Californian children in a 2010 outbreak linked to clusters of unvaccinated individuals. Public health officials strive to combat the misconceptions spread by “anti-vaxxers” such as Jenny McCarthy, but too often their efforts are unsuccessful. A new study published in the journal “Pediatrics” now suggests that these messages may be worse than useless: exposing parents to scientifically based vaccine information can reduce their intent to vaccinate their children.

Surprisingly, this political cartoon may actually be understating the danger of antivaccination beliefs. Courtesy of ixdaily.

Brendan Nyhan, a political scientist at Dartmouth College, and his colleagues wanted to examine the effectiveness of different strategies for promoting vaccines. The researchers interviewed over 1,700 American parents via the Internet to determine their initial attitudes towards vaccines, then exposed them to one of four pro-vaccine messages. The “autism correction” message presented the scientific consensus on the safety of vaccination, relying heavily on statistics and links to journal articles. The “disease risks” message instead focused on the possible dangers of vaccine-preventable illnesses, such as brain damage, deafness, and death. The last two messages, “disease narrative” and “disease images,” employed more personal information, respectively presenting a mother’s harrowing story about her unvaccinated infant and photographs of children riddled with the worst symptoms of measles, mumps, and rubella. Finally, the parents were interviewed again to determine any changes in their beliefs.

Depressingly, none of the messages achieved their intended purpose of increasing vaccination intent. Presenting the “disease risks” message had no effect, while the “disease narrative” and “disease images” methods increased the belief in serious side effects. The “autism correction” approach was partially successful, as parents exposed to this message were less likely to believe in the vaccine-autism link than before reading the information. However, this same group of parents also became less likely to actually vaccinate. Although this effect was due almost entirely to changes in attitudes among parents who had previously reported a distrust of vaccines, the researchers were surprised that factual information could cause a “backlash” response.

In a recent interview with The Communications Network, Nyhan offered a possible explanation for these undesirable results. “It’s uncomfortable for [parents] to be told that this attitude or belief they have is wrong or perhaps based on incorrect evidence, and so they’re going to try to butcher that belief by saying, ‘Oh, why do I not like vaccines? Well, maybe it’s not the autism thing, but I have some other concern.’ In the process of bringing those ideas to mind, they may end up coming to believe more strongly in these concerns or objections they have to vaccines than they otherwise would have.”

Nyhan’s other work has revealed possibilities for countering the backlash effect. As reported by Shankar Vedantam, social science correspondent for National Public Radio, presenting factual information that counters a person’s deeply held beliefs may damage that person’s self-esteem. Boosting the self-esteem of parents before offering vaccine information “might help them take in the new information because they don’t feel as threatened as they might have been otherwise.” While this strategy hasn’t been tested for scientific information, it represents a promising new alternative to previous (and counterproductive) messages. The research suggests that public health officials must take a different approach if they hope to protect children from well-intentioned misconceptions.

 

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