Evaluating the Efficacy of Facebook's Vaccine Misinformation Content Removal Policies

Social media platforms have attempted to remove misinformation about vaccines because it obstructs efforts to end the COVID-19 pandemic. We examined whether Facebook's vaccine misinformation removal policies were effective. Posts and engagements in anti-vaccine pages were reduced to 29% and 23% of pre-policy levels, respectively, but recovered over the subsequent six months. Posts and engagements in pro-vaccine pages were also reduced -- to 68% and 30% of pre-policy levels, respectively. Low-credibility content became more prevalent in anti-vaccine pages and groups, and high-credibility content became less prevalent in pro-vaccine pages. Links between anti-vaccine pages and coordinated inauthentic behavior were also reduced. Our results suggest that Facebook's policies were only partially successful. Facebook's attempts at self-regulation appear to have been resource intensive, and ineffective in the long term.