Study of Vaccine-Related Facebook Ads Reveals Challenges for Public Health

The social media platform’s efforts to improve transparency have led to the removal of ads promoting vaccinations, a new paper finds.

Facebook study
Researchers found that more than half of the Facebook advertisements opposing vaccination were posted by two groups funded by private individuals. (Image: University of Maryland)
November 19, 2019

In the first study of public health-related Facebook advertising, a team of researchers found that a small group of anti-vaccine ad buyers have successfully leveraged Facebook to reach targeted audiences. In a year that has seen the largest measles outbreak in the United States in more than two decades, the role of social media in giving a platform to unscientific anti-vaccine messages and organizations has become a flashpoint.

The study, recently published in the journal Vaccine, was led by George Washington University’s David Broniatowski, associate professor of engineering management and systems engineering, and researchers from the University of Maryland and Johns Hopkins University.

The research calls attention to the threat of social media misinformation as it may contribute to increasing “vaccine hesitancy,” which the World Health Organization ranks among the top threats to global health this year. This increasing reluctance or refusal to vaccinate threatens to reverse the progress made in halting vaccine-preventable diseases, such as measles, which has seen a 30 percent increase in cases globally. 

The research team, co-led by Dr. Broniatowski, UMD’s Sandra C. Quinn and JHU’s Mark Dredze, examined more than 500 vaccine-related ads served to Facebook users and archived in Facebook’s Ad Library. This archive, which became available in late 2018, catalogued ad content related to “issues of national importance.”

The team’s findings reveal that 54 percent of advertisements that opposed vaccination were posted by only two groups funded by private individuals—the World Mercury Project and Stop Mandatory Vaccination. These ads emphasized the purported harms of vaccination.

“The average person might think that this anti-vaccine movement is a grassroots effort led by parents, but what we see on Facebook is that there are a handful of well-connected, powerful people who are responsible for the majority of advertisements. These buyers are more organized than people think,” said Amelia Jamison, a faculty research assistant in the Maryland Center for Health Equity, and the study’s first author.

In contrast, those ads promoting vaccination did not reflect a common or organized theme or funder and were focused on trying to get people vaccinated against a specific disease in a targeted population. Examples included ads for a local WalMart’s flu vaccine clinic or the Gates Foundation campaign against polio.

However, because Facebook categorizes ads about vaccines as political, it has led the platform to reject some pro-vaccine ads that promote vaccination and communicate scientific findings.

“By accepting the framing of vaccine opponents—that vaccination is a political topic, rather than one on which there is widespread public agreement and scientific consensus—Facebook perpetuates the false idea that there is even a debate to be had,” said Dr. Broniatowski, a principal investigator of the study. “This leads to increased vaccine hesitancy, and ultimately, more epidemics.”

Facebook’s decisions about how to handle vaccine messaging have far-reaching and serious consequences, said Dr. Quinn, professor and chair of the Department of Family Science at UMD’s School of Public Health, and a principal investigator on the study.

“In today’s social media world, Facebook looms large as a source of information for many, yet their policies have made it more difficult for users to discern what is legitimate, credible vaccine information,” Dr. Quinn said. “This puts public health officials, with limited staff resources for social media campaigns, at a true disadvantage, just when we need to communicate the urgency of vaccines as a means to protect our children and our families.”

The data gathered for this study is from Facebook’s Ad Archive and was collected in December 2018 and February 2019, before Facebook’s March 2019 announcement of updated advertising policies designed to limit the spread of vaccine-related misinformation.

This study provides a baseline to compare how new policy changes may alter the reach of ads from anti-vaccine organizations, according to the researchers. Those standards were issued in response to the proliferation of anti-vaccination misinformation that coincided with measles outbreaks across the U.S. In early 2019, Facebook  announced it would block advertisements that include false content about vaccines and disallow advertisers from targeting ads to people interested in vaccine controversies, as they were previously able to do.

However, the messengers can simply mutate their messages, virus-like, to avoid the tightening standards.

“There is a whole set of ads that focus on themes of ‘freedom’ or ‘choice’ and that elude the Facebook rules around vaccine ads,” Dr. Broniatowski said. 

The research team will continue to study how anti-vaccine arguments are spreading on Facebook and how the company is responding to demands from public health organizations to clean up its act, Dr. Jamison said.

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