Vaccine Hesitancy and Behavior Change Theory-Based Social Media Interventions: A Systematic Review

"Interventions informed by behavior change theory and delivered via social media platforms offer an important opportunity for addressing vaccine hesitancy."

Achieving adequate vaccine coverage can be threatened by people's concerns about a particular vaccine or vaccination in general. Such concerns are known as vaccine hesitancy. Misinformation spread on social media can contribute to vaccine hesitancy. However, social media can also provide an opportunity to directly address public health issues through two-way communication and thus become a significant health promotion tool that is able to support behaviour change. This review sought to identify social media tools and behaviour change theories used in vaccine hesitancy studies and to assess their implementation and effectiveness in informing the development of interventions for improving vaccination rates.

The systematic review search was performed in PubMed, Scopus, ACM, Cochrane Library, ProQuest, and Web of Science databases for studies published between January 2011 and January 2021 that applied social media tools to increase vaccine confidence or improve vaccination uptake. The literature search yielded a total of 3,065 publications. Twenty articles met the eligibility criteria, 12 of which were theory-based interventions. Appendix C of the paper details the study characteristics, including aims, study design, brief description of the intervention, and results.

In short, 13 interventions used a single type of social media platform (Facebook (n = 9); YouTube (n = 1); Twitter (n = 1); WhatsApp (n = 1)); 3 used general online forums; and 1 used a mixture of social media tools (Twitter, Facebook, and Vine). The other 3 used websites with a built-in interactive component. In terms of the type of intervention, the most common was educational posts (11 articles), followed by dialogue-based interventions (5 articles), interactive website (3 article), and personal reminders (1 article). Examples from the articles detailing each type of intervention are offered. For instance, in the category of educational posts, Lee and Cho investigated whether different message framing had a various impact on the public's behavioural intention to get vaccinated and found that participants who received the loss-framed message on Facebook mostly exhibited a higher level of behavioural intention than those in the gain-framing condition.

Several studies reported using behaviour change theories to inform the design of social media interventions:

• Eight studies used the Health Belief Model (HBM) alone, which posits 4 principal drivers of health behaviours: people's knowledge and perception of the severity of disease and their susceptibility to it; people's perception of the barriers to and benefits of being vaccinated; self-efficacy (their belief in their ability to be vaccinated); and cues to action. Six single-theory (HBM) studies were delivered through educational messages, while 2 were through dialogue-based social media interventions.
• The other 3 combined HBM with the Theory of Planned Behavior (TPB), according to which behaviour can be directly influenced by intentions, which are determined by attitudes (a function of behavioural beliefs), subjective norms, and perceived behavioural control (a function of control belief). The 3 studies that combined HBM with TPB involved interventions delivered through interactive websites.
• Social cognitive theory (SCT) considers 6 elements in addressing behaviour change of individuals: reciprocal determinism (the interaction of the individual, environment, and behaviour), behaviour capability (perceived facilitators and barriers to action), vicarious learning, reinforcements, expectations, and self-efficacy. Compared to the HBM and TPB, SCT focuses more on the social motivation for achieving the behavior change. For example, in one study cited here, the intervention was developed to promote mothers' self-efficacy through group discussion for taking their children to get the influenza vaccination, and the self-efficacy served as the main indicator for design and measured effectiveness.

Theory-based interventions were generally more measurable and comparable and had more evidence to trigger positive behaviour change. Fifteen studies reported effectiveness in knowledge gain, intention increase, or behaviour change. In terms of the mode of delivery:

• Educational messages were proved to be effective in increasing knowledge but less helpful in triggering behaviour change. Four theory-based education posts reported significant results: 1 found higher knowledge gain between before and after the intervention, but no significant increase in vaccination rate; 1 reported the unframing message promoting through Facebook significantly increased the vaccine intention; and the other 2 reported higher vaccination uptake rate due to the intervention. Another nontheory-based educational post also reported a higher vaccination rate, with a 75% increase among the participants after the intervention.
• A theory-based interactive website significantly improved the vaccine knowledge, attitudes and intention to vaccinate, and vaccine uptake.
• Three dialogue-based interventions were reported to be effective in improving people's intention to be vaccinated, one of which was a nontheory-based intervention. Dialogue-based interventions also performed well in increasing vaccine knowledge and awareness, although two studies reported no significant improvement in the vaccine uptake.

The paper goes on to highlight the key findings - the effectiveness, strengths, and limitation of using each social media component and behaviour change theories in the interventions to address vaccine hesitancy - and then to summarise the opportunities and challenges facing future attempts to integrate behaviour change theory and social media interventions as a means of addressing the problem of vaccine hesitancy.

They note that "[s]ummarizing the benefits and limitations of social media interventions is problematic because the studies were carried out in various countries and cultures and are therefore highly context-specific. In general, evidence-based social media interventions have the potential to significantly improve the knowledge, intention, and behavior about vaccines and clear the behavior barriers, especially when compared to other modes such as mass media...and the general internet....Additionally, there are undeniable benefits to using social media - fast access to a wide audience, low cost - so its future is promising, but more evidence-based strategies and studies are needed."

The paper identifies the benefits and limitations of this research. For example, one benefit of theory-based studies is that they are more measurable and replicable. One limitation is that "social media interventions have the potential to exacerbate disparities in healthcare that result from differences between social groups regarding access to the internet and to smartphones...; people without access to social media can become marginalized or completely excluded."

The article discusses some lessons to be learned from existing studies on implementing theory-based social media interventions:

1. Social media alone is not an intervention but a channel for facilitating engagement between people who want to interact with others. Therefore, strategies need to be adopted to ensure the accuracy and coherence of the information being provided, and experts in the relevant fields need to be in place to moderate group discussions.
2. Positive behavioural change is more likely to happen if there is strong trust between the researchers and the group to be reached. Such trust can be fostered by ensuring transparency in all communications, acknowledging participants' concerns, and responding promptly to their questions with tailored information.

The researchers offer some additional guiding reflections for future interventions. For example, considering that vaccine hesitancy is a behaviour in a complex network of related behaviours, the findings of this review highlight the need to use a multitheory framework, such as Behavior Change Wheel, in the development, implementation, and evaluation of any intervention. The researchers also stress the need for future interventions to tailor social media interventions to the specific circumstances and needs of the intended audience.

A concluding thought: "Using behavior change theories to better understand multiple factors, such as beliefs, motivations, and socio-cultural influences, and integrating these theories with social media interventions, is seen as one way to move people from merely receiving information to changing their behavior..."