Abstract: Unraveling the Mechanisms of Social Media Opinion Leadership in COVID-19 Vaccine Promotion

◆ Wenlin Liu, University of Houston
◆ Yan Huang, University of Houston
◆ Omprakash Gnawali, University of Houston
◆ Arsalan Javed, University of Houston
◆ Prerna Makasare, University of Houston

The health promotion literature has long documented the importance of opinion leaders in promoting risk reduction and health prevention behaviors (e.g., Kelly et al., 1991). Opinion leaders are defined as individuals with high credibility who can influence the opinions, attitudes, beliefs, motivations, and behaviors of others (Valenti & Pumpang, 2007). While the mechanisms of opinion leadership in health behavior change are well studied in the offline context, it remains less understood how different types of online opinion leaders, also commonly referred to as “influencers,” may shape individuals’ attitudes towards preventive behaviors like vaccination. Using the COVID-19 vaccine promotion as a research context, this study investigates how two types of opinion leaders, government agencies and celebrities, may differently influence individuals’ attitudes towards the COVID-19 vaccines on social media. While accounts of government agencies maintained an active voice for disseminating vaccine-related information (Puri et al., 2020), individuals also routinely turn to other types of social media influencers, such as celebrities, to engage in discussion related to health risks and preventive behaviors (Myrick & Willoughby, 2021). The study of social media-based opinion leadership is important, not only because individuals are increasingly seeking health information from these platforms, but the infiltration of misinformation on social media makes the issue of credibility especially relevant in the context of health promotion. As government agencies and celebrity influencers are perceived differently as a message source, understanding their differential effects on the public’s message engagement and perceptions is imperative for both theories and practice. In addition to distinct source perceptions, the message strategies social media influencers have employed may also affect the effectiveness of vaccine promotion. Identifying effective content elements that enhance message engagement and perceptions will provide useful knowledge for future influencer campaigns in health promotion. Taken together, the current study examines the extent to which three mechanisms of opinion leadership operates in predicting the public’s supportive attitudes towards the COVID-19 vaccines: (1) the source effect, that is, whether the type of opinion leader (e.g., official organizational sources, different types of celebrities) may influence the extent to which the public accept COVID-19 vaccines; (2) the message effect at the linguistic level – whether the linguistic feature, such as the authoritativeness of the message and efficacy, may play a role; (3) the message effect at the medium level–whether the type of media (e.g., multimedia, visuals) incorporated in the message makes any difference. To test the proposed mechanisms, we collected COVID-19 vaccine-related tweets from 2,410 government agencies and 995 celebrities between January and April, 2021, the onset of releasing FDA-approved COVID-19 vaccines. We employ machine learning classification and Linguistic Inquiry and Word Count (LIWC) to first analyze the message features of tweets from different types of opinion leaders. We then model the effects of message source, linguistic features, and media richness on the level of public support of COVID-19 vaccines on Twitter. Finally, we analyze whether the effects of these message features would be conditioned by the type of opinion leader.