Viral suspicions: Vaccine hesitancy in the web 2.0

A huge and diverse amount of information is available online. In 4 studies, we provided complementary evidence about the psychosocial processes involved in online information gathering about vaccinations and the associated relation with trust in their safety. Study 1 investigated the relation between Italian Google inquiries and vaccine coverage for 0- to 2-year-old Italian children from 2000 and 2015, showing a correlation that turned negative over time. In Study 2, participants randomly assigned to a message providing a dual perspective (false balance condition) endorsed more conspiracy beliefs, which, in turn, reduced trust in vaccines compared with provaccine, antivaccine, and control messages. In Study 3, participants actively selected Google outputs that were in line with their opinion, and this confirmatory bias was particularly strong among participants distrusting vaccination. This association was disrupted by the exposure to provaccine messages, but only if antivaccine alternatives were absent. In Study 4, exposure to online comments questioning the human papilloma virus vaccination influenced attitudes toward the vaccination in a sample of not-yet-vaccinated young women. Practical implications for the way that media cover vaccination topics and for interventions addressing vaccine hesitancy are discussed.