Abstract: This study investigated if and how exposure to Facebook comments about vaccines influences one’s attitude toward the vaccines. In this investigation, comments were examined in light of their effect on attitude toward vaccines through perceived distribution of public opinion on vaccines, and perceived vaccine efficacy was tested as a factor moderating relative effects of comments on perception of public opinion distributions. Results from an experimental study (N = 271) showed that exposure to a greater number of comments in a thread expressing (un)favorable opinions on the flu vaccine led to (un)favorable attitude toward the flu vaccine through a change in perceived distribution of public opinions on the vaccination. The indirect effect of comments on attitude toward the flu vaccine through perceived public opinion distributions was greater among participants with lower levels of perceived vaccine efficacy, while the direct effect of comments on attitude was not significant.
Abstract: Recognizing that social media has become an important place for individuals to acquire vaccine-related information, this study investigated if and how user-generated comments on social media platforms influence individuals’ perception of public consensus regarding and attitude toward vaccines. In addition, perceived vaccine efficacy was considered as a factor moderating the relationship between exposure to social media comments and perceived public consensus. The results of an experimental study showed that an opinion expressed by numerically dominant comments predicted participants’ attitude toward the flu vaccine through shaping perceived public consensus. Moreover, unlike participants with low and medium levels of perceived vaccine efficacy, those with high perceived vaccine efficacy were not influenced by comments when forming perceived public consensus.