Effects of Social Media Comments on Attitude toward Vaccines: The Roles of Perceived Public Consensus and Perceived Vaccine Efficacy

Abstract: Recognizing that social media has become an important place for individuals to acquire vaccine-related information, this study investigated if and how exposure to user-generated comments in social media platforms influences individuals’ attitude toward vaccines. In this investigation, social media comments were investigated in light of their effect on attitude toward vaccines through shaping perception of public consensus, and perceived vaccine efficacy was considered as a moderator of comments’ relative effects. The results from an experimental study (N = 273) showed that an opinion expressed by numerically dominant comments positively predicted participants’ attitude toward the flu vaccine through altering perceived public consensus in the same direction of the comments shown. Moreover, unlike participants with low and medium levels of perceived vaccine efficacy, those with high vaccine efficacy were not influenced by comments when forming perceived public consensus.