Twitter bots, Russian trolls spread misinformation on vaccines

Social media bots and Russian trolls promoted discord and spread false information about vaccines on Twitter, a study has found.

Using tactics similar to those at work during the 2016 United States presidential election, these Twitter accounts entered into vaccine debates months before election season was underway.

Researchers from the George Washington University and Johns Hopkins University in the US examined thousands of tweets sent between July 2014 and September 2017.

They found several accounts, now known to belong to the same Russian trolls who interfered in the US election, as well as marketing and malware bots, tweeted about vaccines and skewed online health communications.

"The vast majority of Americans believe vaccines are safe and effective, but looking at Twitter gives the impression that there is a lot of debate. It turns out that many anti-vaccine tweets come from accounts whose provenance is unclear," said David Broniatowski, an assistant professor at George Washington University.

"These might be bots, human users or 'cyborgs' -- hacked accounts that are sometimes taken over by bots. Although it's impossible to know exactly how many tweets were generated by bots and trolls, our findings suggest that a significant portion of the online discourse about vaccines may be generated by malicious actors with a range of hidden agendas," said Broniatowski.

For example, the researchers found that "content polluters" -- bot accounts that distribute malware, unsolicited commercial content and disruptive materials -- shared anti-vaccination messages 75 percent more than average Twitter users.

"Content polluters seem to use anti-vaccine messages as bait to entice their followers to click on advertisements and links to malicious websites, said Sandra Crouse Quinn, a professor at the University of Maryland.

"Ironically, content that promotes exposure to biological viruses may also promote exposure to computer viruses," she said.

Russian trolls and more sophisticated bot accounts used a different tactic, posting equal amounts of pro- and anti-vaccination tweets.

Researchers reviewed more than 250 tweets about vaccination sent by accounts linked to the Internet Research Agency, a Russian government-backed company recently indicted by a US grand jury because of its attempts to interfere in the 2016 US elections.

The researchers found the tweets used polarising language linking vaccination to controversial issues in American society, such as racial and economic disparities.

"These trolls seem to be using vaccination as a wedge issue, promoting discord in American society," said Mark Dredze, a professor at Johns Hopkins.

"However, by playing both sides, they erode public trust in vaccination, exposing us all to the risk of infectious diseases. Viruses don't respect national boundaries," he said.