When it comes to vaccination, bad news is contagious

In recent years, the controversy about vaccine safety has exploded online. Fueled by pseudoscience, conspiracy theories, and ignorance, a surprisingly large number of people today refuse to vaccinate themselves or their children. According to a 2011 poll, nearly a quarter of Americans have changed their opinion on vaccination in the last five years, and for the vast majority of these people, that change has been in a negative direction. There’s no better tool than social media to spread information—and misinformation—about controversial topics quickly and efficiently, and there has been speculation that these outlets have played a role in heightening concerns about vaccination. But how do opinions about health-related behaviors spread over social media? A group of researchers from Penn State used Twitter to answer this question, and their findings were published in EPJ Data Science last week. During the H1N1 epidemic in 2009, the researchers gathered hundreds of thousands of tweets containing key...