Analysis of the Anti-Vaccine Movement in Social Networks: A Systematic Review

"Without any intervention, surely this [anti-vaccine] movement will grow."

Despite the fact that healthcare professionals remain the main source of health information, including vaccines, the internet has grown as a resource for finding information. Some websites with unreliable content risk generating false beliefs. For example, the novelty of the virus causing the COVID-19 pandemic has led to the rapid spread of false news related to both its origin and its treatment. Moreover, as happens with other vaccines, the quest for an effective SARS-CoV-2 vaccine has generated some false information on the internet and social networks, with some groups saying the future vaccine will have a microchip to control us. The aim of this study was to analyse social networks' information about the anti-vaccine movement.

A systematic review was performed in PubMed, Scopus, CINAHL, and CUIDEN databases. The search queries were: "vaccine AND social network" and "vaccine AND (Facebook[title] OR Twitter[title] OR Instagram[title] OR YouTube[title])". The final sample was n = 12, including only articles published in the last 10 years as of December 2019, in English or Spanish. All selected articles were descriptive cross-sectional studies.

Half of the studies focused on Twitter. They all agreed that the mechanisms to spread the anti-vaccine message on this social network are the use of personal stories, discussion of the risks of vaccines and their components, the business of the pharmaceutical industry, and conspiracy theories, sometimes supported with links to websites based on no evidence. Nevertheless, pro-vaccine tweets and users have more presence on Twitter than anti-vaccine tweets and users.

On YouTube, the most-watched vaccine videos are about personal stories; they had more views than videos by health agencies.

With regard to Facebook, one study found that users who showed negative feelings about vaccines are introduced as a "pro-science" group that tries to give information about vaccines that is supposedly being hidden. Another revealed that comments on this social network mostly speak about distrust towards pharmacists or healthcare providers and include negative experiences with vaccines. In terms of interaction, comments in favour of immunisation receive more "likes" than those against, although the latter group consumes more content. As on Twitter, antivaccine users based their posts and comments on personal stories, vaccine risks, vaccine components, distrust in the pharmaceutical industry, and conspiracy theories. Even though pro-vaccine users and posts have more presence, anti-vaccine users seem to grow more cohesively on Facebook than pro-vaccine groups.

Another method used by the anti-vaccine groups to attract different users is debate generated by bots and trolls about vaccination - e.g., about the motives of pharmaceutical companies. The methods used by groups against vaccination on social networks are diverse and in many cases are useful for their task.

Reflecting on the findings, the researchers stress that, "The influence of the anti-vaccine movement on social networks can be prevented with strategies that are already working, like creating social networks accounts for official health organizations or modifying the search logarithm of social networks, showing the official information from verified sources first when a user looks for information about vaccines or the COVID-19 pandemic (as it is being done on the main social networks)....Furthermore, a strong emphasis on parents’ education about how to find and trust checked information in health institutions should be taken into account....This study shows the need for greater training for the population to learn how to detect fake information and, on the part of health agencies, to be attentive to possible misinformation that may arise and refute it with true and accessible data in a simple language accessible to the population. They should also promote strategies to try to reach more people on the net to combat misinformation and fake news."