Outbreaks of vaccine-preventable illnesses have made frequent headlines in the news over the past few years. Some recent, well-publicized outbreaks in the United States include 49 cases of measles in California in the first three months of 2014 and 123 confirmed cases of mumps, as of April 3, in the Columbus, Ohio, area. Driving the outbreaks, in part, is reduced compliance with MMR vaccination requirements.
Overall, according to the 2011 National Immunization Survey, U.S. MMR vaccination rates among children 19 to 35 months of age exceeded the target rate of 90%, but 15 states fell below that threshold, with some areas significantly lower as a result of clusters of undervaccinated children. The prevalence of vaccine-safety fears and increasing requests for exemptions make maintaining optimal vaccination rates difficult.
In an effort to increase compliance, researchers used a nationally representative survey of 1,759 parents of children 17 years old and younger to test four likely interventions: debunking the belief that MMR causes autism; providing information about the symptoms and adverse effects of mumps, measles, and rubella; sharing a story about an infant who almost died from the measles; and showing images of children with the diseases. The first three interventions used language taken almost verbatim from the Centers for Disease Control and Prevention.
The researchers found that debunking the autism-MMR link did in fact reduce misperceptions about the connection; even so, it didn't reduce parents' concerns about adverse effects and in fact, among those parents with the least favorable attitudes toward vaccination, it reduced the intention to vaccinate. Additionally, emphasizing the risks of the diseases and showing images of sick children only increased the parents' fears.
Because none of the interventions devised by public health authorities appears to increase parents' intention to vaccinate their children, the study authors conclude that "the best response to false beliefs is not necessarily providing correct information," and that scare tactics can backfire. What approaches can work remains to be seen; subtler messaging might be effective, and having a trusted source, such as a health care provider, deliver the message could make a difference.-Laura Wallis
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