Abstract
Although messenger RNA (mRNA) technology revolutionized vaccine creation, its use is threatened by unwarranted fear that DNA left over from the vaccine manufacturing process could integrate into recipients' DNA, increasing cancer and heritable risks. Drawing on the mental model theory of reasoning, our two preregistered interventions undercut these problematic conclusions. They do so by testing the effectiveness of two mental model-based interventions juxtaposing problematic claims with visualized or verbally explained models of basic biological and vaccination systems. Study 1: a) graphically modeled how mRNA COVID-19 vaccination works (Model 1); b) verbally modeled ways in which cells protect themselves from foreign DNA (Model 2); and c) provided ancillary material designed to bolster perceptions of mRNA vaccination safety. Study 2 deployed an animation of the cell-protection model (Model 2), alone, and in combination with Study 1's messaging. Neither the mRNA vaccine nor the DNA protection model explicitly acknowledged the problematic DNA-integration claim. Both preemptive (before) and rebuttal (after) positioning of the models were effective. Within-person analyses suggested that preemptive positioning may be somewhat more effective than rebuttal positioning. Some positive effects of exposure to the modeled knowledge messaging condition in Study 1 persisted 2 mo after exposure.