Study Examines Facebook User Comments on Vaccines

Updated 12/5/2016

The Internet is loaded with peer-reviewed, science-based data—as well as plenty of misinformation—regarding vaccines. Researchers recently studied how pro- and anti-vaccination opinions on Facebook were expressed to understand how people discuss and spread these views.

In their new paper, A Comparison of Language Use in Pro- and Anti-Vaccination Comments in Response to a High Profile Facebook Post, available through online-early access to the journal Vaccine, researchers from the University of South Wales in Sydney, Australia, and La Sierra University in Riverside, California, examined prominent Facebook posts about childhood vaccination. Their findings shed light on opposing stances on vaccines at a time when Internet use has made misinformation on vaccination readily available, causing heightened concern about the safety of child immunization shots.

“Prevalent in our study and others are references to distrust in government and conspiratorial thinking,” say study authors Kate Faasse, PhD, and Leslie R. Martin, PhD. “This presents a challenge for health officials to communicate accurate and evidence-based information about vaccination—because they are portrayed by anti-vaccination viewpoints as part of the problem.”

The Centers for Disease Control and Prevention (CDC) sets vaccination policy recommendations, which go to state legislatures and public health officials in state health departments to make and enforce each state’s vaccine laws. According to the CDC, more than 9 in 10 children in the United States have received the recommended vaccination dosages for measles-mumps-rubella, diphtheria, tetanus, pertussis, and varicella. And in general, parents of today’s young children in the developed world have never had to live through an epidemic, such as the deadly smallpox, cholera, or polio outbreaks of the past, in large part due to the vaccines now widely available to prevent these diseases. However, each state also has its own policies allowing for medical exemptions that excuse a child from vaccination if their doctor says it would be detrimental to the child’s health. Most states also allow religious and philosophical exemptions, which a parent can exercise if vaccination goes against their family’s personal beliefs. A median of 1.7% of American children are not immunized due to exemptions, and in some states such as Maine, Vermont, Wisconsin, Colorado, Idaho, and Oregon, 4% or more of children enrolled in kindergarten have been exempted from receiving one or more vaccinations.

Unvaccinated individuals tend to cluster, says the CDC, which puts communities at risk for outbreaks, such as the measles outbreak that occurred in 2015 among unvaccinated children who visited an amusement park. The unvaccinated benefit from the “herd immunity” that occurs when community members are immunized for contagious diseases helps impart immunity to the un-immunized members and their communities at large, resulting in fewer disease outbreaks. Pockets of unvaccinated children, though, can become a reminder about just how vulnerable we still are to contagious diseases.

The recent study zeroed in on the language of Facebook users surrounding the issue of vaccination, examining the response to a prominent photograph posted by Mark Zuckerberg of his daughter, with the caption “Doctor’s visit—time for vaccines!” At the time of the study, the picture had received more than 3.4 million likes and 84,000 comments. The researchers used a text analysis program to compare the statements and claims in the comments. Their aim was to investigate the types of arguments and language used by pro- and anti-vaccination individuals within the same conversational context in an effort to better understand underlying thought processes and inform future attitude- and behavior-change attempts. They hypothesized that due to the science supporting the safety and efficacy of vaccines, comments by those who were vaccine-hesitant would show less evidence of analytic thought and would use more risk-related, anxiety-related, and health-related words.

What the study found was not the expected irrational or emotional argument style from those whose comments were against vaccines. “The anti-vaccination comments contained linguistic markers of analytical thinking, characterized by categorical language use, often appearing as factual (or in this case, pseudo-factual) and logically structured statements that mimic valid scientific information. This, as well as relatively lower use of anxiety-related words (giving the impression of confidence in one’s correctness), may make anti-vaccination arguments particularly compelling for uncertain parents seeking information about childhood vaccination,” write the authors about their findings. “This suggests a group attempting to provide scientific explanations for an unscientifically-backed perspective, as well as broader concerns about the monetary motivations of medical professionals, scientists, pharmaceutical companies, and governments.”

The researchers also noted that pro-vaccination comments had a significantly more anxious nature, along with their greater family-related content. “It may be that these individuals have a greater awareness and understanding of the scientific data,” write the authors, “and thus, a greater cause to worry, especially about their own families whom they believe may be harmed by the failure of others to accept vaccinations.”

These linguistic profiles show an apparent mismatch between the concerns and focus of pro- and anti-vaccination comments, say the authors. Their findings provide insight into how the medical community can better develop education to enhance the public’s understanding of science and create accurate messaging around the health and biological mechanisms of vaccination to effectively shift the views of those who are vaccine-hesitant.

“Taking steps to foster trust in health officials, perhaps including greater openness and education about scientific research and how recommendations are formulated, may be a useful step,” say Drs. Faasse and Martin. “We may also need to consider other people who are considered trusted sources of health information who might more effectively communicate information about vaccinations. One of the challenges with social media is to actually reach the people who hold negative perceptions of vaccinations—they may well not be the same people who regularly connect with official social media health channels.”