Effect of falsely balanced media coverage of the autism-vaccine controversy on vaccine safety perceptions and behavioral intention

The goal of this study was to employ experimental methods as a useful tool for measuring and comparing the effect of falsely balanced reporting of the autism-vaccine controversy (AVC) on individuals' vaccine intentions and certainty perceptions of vaccine safety. False balance refers to a reporting style in which a perspective supported by an overwhelming amount of evidence (i.e., no link exists between vaccines and autism) is equally presented alongside another perspective holding comparatively less or no evidence (i.e., a link exists between vaccines and autism), and without mention for where the strength of evidence lies. Between September and December 2011, 320 undergraduates were randomly assigned to read one of four actual news articles about the AVC. Articles were coded as either falsely balanced (discussing claims both for/against an autism-vaccine link), anti-link (discussing claims against an autism-vaccine link only), pro-link (discussing claims for an autism-vaccine link only), or control (article about non-health related topic). Dependant variables included (1) certainty of vaccine safety and (2) intention to vaccinate. Participants assigned to the false balanced condition (n=80) were less certain that vaccines were safe to receive and had a lower intention to have their future children vaccinated relative to the other conditions. Based on these results, we examine the journalism norms or standards of conduct that may shape falsely balanced coverage and how health officials can effectively communicate vaccine safety to the public based on these considerations. We also discuss future research opportunities with other populations, including vaccine “decision-makers” such as parents.