Fake News and Advertising on Social Media: A Study of the Anti-Vaccination Movement

Online sources sometimes publish information that is false or intentionally misleading. We study the role of social networks and advertising on social networks in the dissemination of false news stories about childhood vaccines. We document that anti-vaccine Facebook groups disseminate false stories beyond the groups as well as serving as an “echo” chamber. We also find that after Facebook's ban on advertising by fake new sites, the sharing of fake news articles on Facebook fell by 75% on Facebook compared to Twitter.