At this point, it's old news that Russia is intervening in US society in part by using troll farms organized by its Internet Research Agency. While the farms' most high-profile activity was supporting Donald Trump during the 2016 election, the trolls were active both before and since, largely in attempts to enhance existing divisions in US society.

One divisive area they've latched on to is vaccination, which has been the subject of numerous public controversies of late. But, while it was clear Russian trolls were talking about vaccines on social media, it wasn't clear what they hoped to accomplish. A new study suggests their goals are twofold and create the risk of politicizing an issue that has largely been free of partisan politics.

The results provide a preview of where we might be going with coronavirus misinformation and why things might get worse once a vaccine becomes available.

A non-political controversy

Vaccines are an unusual issue for the US public. As the stories we linked above make clear, vaccine safety has become a major controversy, and there is regular legislative action that pushes that controversy to the forefront. Yet the issue has managed to avoid association with any particular ideology or policy. The vast majority of the US public accepts the medical community's conclusions that vaccines are generally safe and effective as well as a critical component of disease control.

The rare individuals who reject this conclusion tend to be at the extremes. On the left, some people distrust any effort that involves businesses like the pharmaceutical companies, while on the right, the opposition focuses on the government's role in vaccination programs.

Nevertheless, the public controversy makes vaccine safety an obvious target for Russia's Internet Research Agency (IRA), with its goal of stoking divisions within the US public. And indeed, social media posts about vaccine safety from IRA accounts started appearing as early as 2015. But it wasn't clear whether the posts were part of a strategic effort or just an incidental byproduct of the trolls' attempts to create the illusion that their accounts belonged to real humans. So, a team of three researchers (Dror Walter, Yotam Ophir, and Kathleen Hall Jamieson) decided to look more closely at the IRA's activities.

To do so, the researchers took advantage of a large collection of accounts that Twitter had identified as being run by the IRA and shut down. Nearly 3 million of the tweets from those accounts have been preserved from a three-year period, allowing for a detailed analysis of the bots' behavior.

What bots mention vaccines?

While the bots were involved in the vaccine controversy, that was a relatively minor part of their content, accounting for just under 2,000 tweets, or less than 0.1 percent of the total. But vaccine tweets weren't evenly distributed among the accounts. To find out more, the researchers used a machine-learning tool to categorize the accounts based on their word use and the subjects they discussed.

The algorithm determined there were nine clusters of accounts, several of which never mentioned vaccines. For example, a number of the bot accounts were involved in attempts to manipulate the popularity of hashtags and didn't discuss vaccines. Similarly, a set of anti-Ukraine accounts that focused on supporting Russia's annexation of Crimea were, not surprisingly, devoid of vaccine content.

But a number of other categories of accounts did make vaccine-focused posts. Some of those, however, weren't especially informative. Three types of accounts focused on news and events, which sporadically mentioned vaccine stories, but their content was rare and either neutral or contained a balanced mix of pro- and anti-vaccine items.

One unexpected group that did mention vaccines was a set of accounts that pretended to be African Americans. Vaccines were a small component of their posts (0.03 percent), but over 10 percent of the accounts in this group mentioned them at least once. The posts were roughly evenly mixed between pro- and anti-vaccine statements, with the anti-vaccination ones largely focusing on an anti-corporate message.

Two other groups that were involved with vaccine messaging were collections of pro- and anti-Trump accounts. The anti-Trump/liberal group had a rate of posting (0.5 percent) that was relatively high and was the most pro-vaccine, with 38 percent of the post promoting them and another 52 percent being neutral. The pro-Trump group, by contrast, had a much lower rate of tweeting about vaccines (0.04 percent), but 17 percent of the accounts in this group mentioned the topic at least once. Unfortunately, over half their tweets were anti-vaccination.

Accidental or intentional?

So do Russian trolls view vaccines as a possible political wedge issue? It's a bit difficult to tell. Many of the accounts analyzed by the authors tried to maintain a diverse mix of topics in their posts, in part to avoid the automated systems Twitter uses to identify bot accounts. As such, at least some of this might have simply been an attempt to try to make an account look like it belonged to an actual human with diverse interests. But that doesn't necessarily explain why there's a difference between how the two types of accounts approached vaccines or why the trolls decided anti-pharma agitation was something consistent with African American behavior.

The researchers note that there is some evidence that vaccine safety is becoming politically polarized. And it is consistent with some of the response to the coronavirus outbreak, with medical experts being targeted by pro-Trump groups.

But the real worry here is that the trolls' activity will take what had been a fringe controversy and help turn it into one that matters for partisan identity. Even if their initial messaging was random, their effective mimicking of identities may cause those with similar identities to adopt the same stance, leading to an amplification.

That's dangerous now, during a public health emergency. But it can have long-lasting consequences. To begin with, establishing herd immunity to coronavirus without wide-scale death and disruption will require the widespread use of a vaccine once it is available. And vaccines will remain central to public health long after this pandemic subsides.

Optimistically, however, it's also possible that the problems already caused by the pandemic will lead to widespread acceptance of the vaccine when it becomes available and help keep anti-vaccination attitudes on the fringes of public opinion.

American Journal of Public Health, 2020. DOI: 10.2105/AJPH.2019.305564 (About DOIs).