We are in the golden age for vaccines. We have dozens of highly effective vaccines licensed for infectious disease, promising new technologies contributing to massive advancement of vaccine development, and several promising vaccines on the horizon. Unfortunately, vaccines have been a victim of their own success. With the drastic reduction of once-devastating diseases like whooping cough and measles, it seems like some parents think that the vaccines themselves are the new danger. But the threat isn’t gone; it’s been kept at bay by vaccinations. With clusters of vaccine-hesitant individuals especially worrisome, we need to find effective ways to convince people that the true danger is still disease.

Concerns about the chemical components of vaccines, government mandates of vaccinations for school entry, and “Big Pharma” pushing vaccination seem unchanged when facts countering these claims are presented. Most of the existing research focuses on providing education or addressing parental vaccine attitudes, but rarely addresses the values people hold. We know that a host of factors influence how people retain and use facts in their decision-making, and most of us don’t make our decisions rooted in emotionless logic. But if the facts alone don’t work, then what does?

Perhaps we haven’t been looking in the right place. Recently, the focus has been on educational interventions, appeals to altruism, and statistics, when the answer may lie in an unexpected place, like political science and social psychology. We suspected that individual values might hold the key – after all, there’s a reason that many politicians will appeal to their voters’ values – so we sought to determine if there is a relationship between values and vaccine hesitancy. We found a link between vaccine hesitancy and values of purity and liberty, which is especially informative given that many “traditional” pro-vaccine arguments focus on other values: fairness and protecting oneself and others from harm. Perhaps, if we incorporate these additional values into pro-vaccine messages, they’ll resonate more with hesitant parents and be more effective at convincing people to get vaccinated.

So, what are these values, and what do they mean? We used a framework known as Moral Foundations Theory, a relatively recent development in social psychology that can be used to describe the moral palate. Multiple broad values – authority, care, fairness, liberty, loyalty, and purity – guide our intuitions as we make snap judgements about whether something is right or wrong. Not everyone uses these values in the same way. Just as some people respond more to sweet than salty flavors, so too do some individuals prioritize certain foundations over others. The scores an individual receives on the Moral Foundations Questionnaire reflect the strength of their emphasis on particular foundations; the higher the score, the larger of a consideration it is in their decisions.

In our first study, our team at Emory recruited over one thousand participants online and asked them questions about their vaccine attitudes and their endorsement of the moral foundations. Vaccine attitudes were measured using the Parent Attitudes about Childhood Vaccines short scale, a standardized assessment method. We found that parents with moderate vaccine concerns scored similarly to their less-concerned counterparts on all foundations except purity. Moderately concerned parents were twice as likely to have a high purity score. Compared to parents with the lowest hesitancy, parents in the highest category were twice as likely to have high scores for both purity and liberty, and twice as likely to have a low score for authority. Essentially, hesitant parents are more likely to strongly emphasize values of purity and liberty, and less likely to strongly emphasize values of authority, than non-hesitant parents.

Our colleagues at Loyola (Cara Ray, Kala Melchiori, and Jeff Huntsinger) suspected that common claims on anti-vaccination websites, like “Vaccines contain poisons/toxins/contaminants” and “Vaccine mandates are excessive government control” might especially resonate with hesitant parents because they stimulate these purity and liberty values. In a second study, we asked parents to rate their strength of belief in vaccine claims themed around both purity and liberty, which were adapted from the claims we commonly saw on anti-vaccination websites. This second study not only replicated the first study’s purity and liberty findings, but also demonstrated that high scores for these two foundations were linked with stronger belief in these purity- and liberty-themed vaccine claims. This suggests that stronger endorsement on these foundations may make individuals more likely to believe claims that resonate with these values, even if the claims themselves are factually inaccurate.

While these findings might provide a potential mechanism for vaccine attitude formation and change, it’s important to note that our results are correlational, not causal. Moreover, accurately identifying a phenomenon doesn’t automatically translate to successful interventions. All the same, these findings suggest that current messages promoting vaccination – which overwhelmingly tend to concentrate on care/harm and in some cases fairness – may not be targeting the most salient moral concerns among vaccine-hesitant parents. This could open up a new avenue for pro-vaccination messaging to incorporate purity and liberty values. If we can better connect with concerned parents, they might be more receptive to hearing what we have to say. What if other healthcare decisions and attitudes, like those about palliative care or testing for sexually transmitted diseases, are also associated with moral foundations? How can we leverage such associations to promote overall public health? We are eager to learn the answers.