On Twitter, anti-vaccination statements appear to be socially contagious while pro-vaccination statements are not, according to a team of researchers
who tracked 318,379 pro- and anti-vaccine messages on the social networking website.
Starting in 2009, the team from Penn State University tracked the vaccine-related messages that Twitter users were exposed to, and then observed how those users expressed their own opinions about a new H1N1 influenza vaccine. Positive sentiments would be, for example, an expressed desire to get the H1N1 vaccine, while a negative statement would be a belief that the vaccine caused harm.
Viral sentiments spreading via Twitter...Twiruses??