Journal of health communication
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During and after the 2011 Republican presidential debate, a candidate questioned the safety of HPV vaccine. The authors aimed to determine the effect of these comments on parents. A national sample of 327 parents with adolescent sons ages 11-17 years completed online surveys in fall 2010 (baseline, about 1 year before the debate) and 2011 (follow-up, about 1 month after the debate). ⋯ Parents aware of the comments had a larger increase between baseline and follow-up in the belief that HPV vaccine might cause short-term health problems compared with parents who were not aware. Although the candidate's comments may have increased some parents' beliefs about the short-term harms of HPV vaccine, the comments had no effect on other beliefs, willingness to vaccinate, or behavior. Having accurate information about HPV vaccine that is readily available to the public during such controversies may diminish their effect.
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Media coverage of contentious risk issues often features competing claims about whether a risk exists and what scientific evidence shows, and journalists often cover these issues by presenting both sides. However, for topics defined by scientific agreement, balanced coverage erroneously heightens uncertainty about scientific information and the issue itself. In this article, we extend research on combating so-called information and issue uncertainty using weight of evidence, drawing on the discredited autism-vaccine link as a case study. ⋯ Postexposure issue uncertainty decreased-in other words, issue certainty increased-from preexposure levels across all conditions. Moreover, weight-of-evidence messages were associated with positive vaccine attitudes indirectly via reduced information uncertainty (i.e., one's belief that scientific opinion and evidence concerning a potential link is unclear) as well as issue uncertainty. We discuss implications for risk communication.