Facebook chatter from the anti-vaccination movement now frames the issue as one of civil liberties, a new study finds.

As a COVID-19 vaccine gets closer to becoming a reality, opposition from so-called anti-vaxxer groups could become a political movement, researchers warn.

For the study, the investigators looked at more than 250,000 posts on 204 Facebook pages opposing vaccines between October 2009 and October 2019.

Opposition has traditionally centered on medical safety and government conspiracy theories. But vaccine opponents have recast their objections, saying it is a civil right to refuse vaccination.

The latest recent spike in the anti-vaxxer movement was a 2019 Facebook campaign with posts that included a U.S. state in their title, such as “Michigan for Vaccine Choice.” The posts cited vaccine safety concerns and alternative medicines, and encouraged opposition to vaccine mandates.

“Starting in 2019, we saw a large increase in these state-level pages, especially in places considering vaccine-related legislation,” said study co-author Mark Dredze, an associate professor of computer science at Johns Hopkins University, in Baltimore.

“These pages make it easy for vaccine opponents to know how to vote in their local elections to make it easier to opt out of vaccination,” Dredze added in a Hopkins news release.

There were two prior events that also changed the online discourse, the study authors reported.

The first event was a measles outbreak at Disneyland in 2015. This event led to Facebook pages that framed vaccine refusal as a civil right, and talked about political mobilization and totalitarianism.

Then, in 2016, anti-vaccination posts ramped up after the release of “Vaxxed,” a film by a discredited former doctor. Many posts that promoted the movie framed vaccine refusal as a civil right.

Study co-author David Broniatowski explained that “framing vaccine refusal as a civil right allows vaccine opponents to sidestep the science, and instead debate about values — especially, the value of freedom of choice. However, this is a case where one person’s exercise of that freedom can hurt everyone else.”

Broniatowski, an associate professor in the School of Engineering and Applied Science at George Washington University, in Washington, D.C., and his colleagues warned that vaccine opponents are gaining political clout as they become organized.

The report was published online Oct. 1 in the American Journal of Public Health.

More information

For more on the science of vaccines, head to the U.S. Centers for Disease Control and Prevention.