Effects of Facebook Comments on Attitude Toward Vaccines: The Roles of Perceived Distributions of Public Opinion and Perceived Vaccine Efficacy

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.

Development of a US trust measure to assess and monitor parental confidence in the vaccine system.

Abstract: To develop a Vaccine Confidence Index (VCI) that is capable of detecting variations in parental confidence towards childhood immunizations centered on trust and concern issues that impact vaccine confidence. Methods: We used a web-based national poll of 893 parents of children <7 years in 2016 to assess the measures created for the Emory VCI (EVCI). EVCI measures were developed using constructs related to vaccine confidence identified by the U.S. National Vaccine Advisory Committee (i.e., “Information Environment”, “Trust”, “Healthcare Provider”, “Attitudes and Beliefs”, and “Social Norms”). Reliability for EVCI was assessed using Cronbach’s alpha. Using the variables related to each of the constructs, we calculated an overall EVCI score that was then assessed against self-reported childhood vaccine receipt using chi-square and the Cochrane-Armitage trend tests. Results: Respondents’ EVCI scores could range from 0 to 24, and the full range of values was observed in this sample (Mean = 17.5 (SD 4.8)). EVCI scores were significantly different (p ≤ 0.006 for all comparisons) between parents who indicated their child(ren) received routinely recommended vaccines compared with parents who indicated they had delayed or declined recommended immunizations. There was also a significant, consistent association between higher EVCI scores and greater reported vaccine receipt. Conclusions: We developed EVCI to reliably measure parental vaccine confidence, with individuals’ scores linked to parental vaccine-related attitudes, intentions, and behaviors. As such, EVCI may be a useful tool for future monitoring of both population and individual confidence in childhood immunization.

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.