Marketplaces of Misinformation: A Study of How Vaccine Misinformation Is Legitimized on Social Media

By Giandomenico Di Domenico, Daniel Nunan and Valentina Pitardi

Fighting health misinformation is one of the major challenges of our times. Misinformation and conspiracy theories about vaccines spread through social media and shape how people make health decisions. Despite attempts by social media firms to tackle vaccine misinformation, it has become endemic, with estimates that more than 100 million Facebook users have been exposed to some form of it. Social media platforms seem to be catalysts for the spread of misinformation, but where does the misinformation come from in this first place? Why is misinformation accepted by the public? Our latest work, published in the Journal of Public Policy and Marketing, addresses these questions by identifying how vaccine misinformation that originates in books sold via online marketplaces gets legitimized and spread through social media.

Though misinformation touches on almost all health care areas, vaccine misinformation represents the most high-profile current manifestation of this problem. Health information is complex and individuals rely on health professionals to interpret it. However, sometimes those with professional qualifications are behind the spread of misinformation. They exploit the popularity of the online world to promote their contents, building a social media audience that they influence by leveraging their credentials. Alongside social media, the rise in the self-publishing of books through marketplaces such as Amazon gives these “health influencers” the ability to spread misinformation further. Books are still widely perceived as a source of credible, in-depth expert knowledge. When content from these books reaches social media, its reach is magnified, posing a threat to individual and public health.

In our first study, we find that “health influencers” use various cues to legitimize their content. We analysed 28 vaccine misinformation books descriptions on Amazon and the corresponding 679 Facebook posts mentioning them. We found that the book authors create arguments against pharmaceutical firms by leveraging their medical credentials. Even if the author’s medical credential had been revoked by health authorities, it was still influential in legitimating the misrepresentation of scientific evidence.

In our subsequent studies we find that credentials increase the perceptions of misinformation legitimacy for people who are generally supportive of vaccines, while it decreases the same perceptions for vaccine hesitant people. This result highlights the core role of prior beliefs in information processing: people who are supportive of vaccines tend to trust the apparent expertise of people who share medical information and therefore are more prone to legitimize it.

These findings help to uncover the relationships between different online platforms in seeding the spreading of false beliefs about vaccines. While policy usually focuses on individual platforms to curb the spreading of misinformation, we suggest that more effective policy interventions acknowledge the flow of information between online platforms.

We also show that the legitimacy of vaccine misinformation is conveyed through the misuse of medical credentials. Policy-makers and social media firms could be more active in verifying credentials when used to legitimize misinformation. This would ensure a correct use of credentials, a delegitimization of vaccine misinformation and limit its spreading through social media. Ultimately, this would increase the quality of information flowing in digital environments.

Article Details
Marketplaces of Misinformation: A Study of How Vaccine Misinformation Is Legitimized on Social Media
Giandomenico Di Domenico, Daniel Nunan, Valentina Pitardi
First published July 12, 2022
DOI: 10.1177/07439156221103860
Journal of Public Policy and Marketing

About the Authors