The study, published in the journal Vaccine, was conducted by researchers at the University of Maryland, the George Washington University and Johns Hopkins University and looked at how Facebook advertising was used to promote both pro and anti-vaccination messages.
It found that a small group of “well-connected, powerful people” promoting broad anti-vaccination messages had successfully leveraged the platform’s targeted advertising service to reach select audiences. Specifically, 54% of all anti-vaccine adverts were posted by two privately funded groups: the World Mercury Project and Stop Mandatory Vaccination.