Russian trolls weren’t just trying to cause division in U.S. politics. A new study shows that they were also trying to stoke divides in one of the country's most heated debates around public health: vaccinations.

Russia-linked social media bots pushed divisive speech and misinformation on Twitter on both sides of the preexisting vaccine debate, according to research led by George Washington University and published Thursday in the American Journal of Public Health.

"These trolls seem to be using vaccination as a wedge issue, promoting discord in American society," the study's authors said.

The team of researchers, which also includes academics from the University of Maryland and Johns Hopkins University, analyzed a database of Russian troll accounts assembled by NBC News and found that the accounts were "significantly more likely to tweet about vaccination than are average Twitter users." The research spanned from July 2014 to September 2017.

The researchers also found several tweets belonging to accounts that were identified by Congress as being linked to the notorious Internet Research Agency, a Kremlin “troll farm.”

These accounts posted messages both against and for vaccination in roughly equal amounts.

While the number of vaccination tweets sent by the Russian trolls was a small percentage compared to the overall volume of tweets sent on Twitter in a given day, or even compared to the overall total number of tweets sent by the trolls themselves, the study highlights how social media-based propaganda efforts from Russia were not solely focused on the 2016 election and have been found to push divisive content related to a variety of topics such as race relations and even health.

Though the conflict between those who believe in the scientific basis for the benefit of vaccines and those who link them to unfounded health concerns had raged for years, the topic became another issue the Russian trolls seized upon to widen existing rifts in America and turn citizens against each other.

"Thus, health communications have become 'weaponized,'" the researchers wrote. "Public health issues, such as vaccination, are included in attempts to spread misinformation and misinformation by foreign powers."

An NBC News analysis of over a million tweets sent by identified Russian trolls published by the data journalism website FiveThirtyEight and Clemson University researchers found over 1,000 examples of tweets that mention vaccines, often spreading divisive misinformation and discredited theories.

“The Vaccine Hoax is Over — Secret Documents Reveal Shocking Truth,” wrote Russian troll _NICKLUNA_ in February 2017. “Autism Rates in California Have Skyrocketed Following Mandatory Vaccination Bill,” tweeted Amelie Baldwin, a prolific Russian troll, in December of 2016.

The researchers found that the Russian trolls even came up with their own hashtag to promote especially divisive anti-vaccination messages during a spree in February 2015.

“The production of a #vaccine is disgusting #VaccinateUS,” said one account.

“#VaccinateUS #vaccines can cause mental disorders!,” said another, going on to tweet eight more times using the same Russian troll-created hashtag.

The researchers compared the likelihood of different kinds of bots and Russian trolls to tweet about vaccines and engage in partisan social media conversation around vaccines. “Sophisticated bots” and Russian trolls were several times more likely than traditional spam bots to tweet about vaccines, according to their analysis.

Bots' likelihood of tweeting about vaccines compared with average Twitter users between July 14, 2014 and Sept. 26, 2017 AJPH / Broniatowski et al.

The trolls were opportunistic conversation disrupters. Sometimes the same account would take two sides of the same issue.

In April 2017, Baldwin tweeted this anti-vaccine sentiment: “Vaccine dangers are hidden from parents by the FDA using a simple TRICK - make the placebo as toxic as the vaccine so both have = reactions”

A month later she seems to have switched positions.

“WHO recommends vaccination with 1st dose of #hepatitisB vaccine within the first 24 hours of life #VaccinesWork,” the account tweeted in May.

In reality, there is no legitimate debate about the safety or benefits of vaccines. While no medical group claims vaccines are completely safe, the Centers for Disease Control and Prevention, National Institutes of Health and dozens of academic researchers independent of the federal government have shown the benefits of vaccines both to individual children and adults and to the population at large.

That has not stopped anti-vaccination groups from finding success online, with numerous internet forums dedicated to the false belief that vaccines are harmful to children.

Other researchers have started to look into how the anti-vaccination movement has taken off in America. A recent study found that the number of parents applying for nonmedical exemptions to vaccinations had risen from 2009 to 2017 in 12 of the 18 states that allow them. Fake accounts set up by the trolls to imitate regional news sources were also active in some of the same geographic regions.

“What we are seeing is pockets of intense anti-vaccine activity,” said Dr. Peter Hotez, a pediatrician and dean of the National School of Tropical Medicine at the Baylor College of Medicine, one of the authors of the study, published in the Public Library of Science journal PLoS Medicine.

“A social movement of public health vaccine opposition has been growing in the United States in recent years; subsequently, measles outbreaks have also increased,” Hotez and colleagues wrote.