The Information Ecosystem of Online Groups with Anti- and Pro-vaccine Views on Facebook

Opposition and hesitancy to vaccination have been one of the major threats to global health. Social media sites have been suspected as a breeding ground of misleading narratives about vaccines, but little is known about how pervasive anti-vaccine views are on the world's largest social media, Facebook. Here, we study the prevalence of online groups on Facebook with anti- and pro-vaccine views and the information ecosystem that enables the production and dissemination of anti-vaccine narratives, using the largest collection of Facebook data on this issue to date. The results reveal that 74% of posts each month on average were generated by anti-vaccine groups. It is also shown that anti-vaccine groups had increasingly more relied on relatively credible sources while their posts using low credibility sources were less than 2% and recently decreasing. Furthermore, anti-vaccine groups depended more on their exclusive sources and utilized sources representing more conservative or far-right political views than pro-vaccine groups did. The findings suggest that expansive and targeted interventions are urgently needed to curb the circulation of online narratives against vaccination.