The Influence of Political Ideology and Trust on Willingness to Vaccinate

"In light of the increasing refusal of some parents to vaccinate children, public health strategies have focused on increasing knowledge and awareness based on a 'knowledge-deficit' approach. However, decisions about vaccination are based on more than mere knowledge of risks, costs, and benefits."

This paper uses a nationally representative internet survey in the United States (US) to investigate socio-political characteristics to assess attitudes about vaccination. In particular, it considers how political ideology and trust affect vaccination beliefs for flu, pertussis (whooping cough), and measles. It investigates two forms of trust: trust in government medical experts (such as the US Centers for Disease Control and Prevention, or CDC) and trust in primary health care providers (such as paediatricians or family doctors). Furthermore, it looks at the relationship between trust and ideology, where ideology is conceived as a continuum ranging from very conservative, to moderate, to very liberal.

The paper introduces the study by citing Douglas and Wildavsky, who use four categories - hierarchical, individualist, fatalist, egalitarian - to understand how each cultural group applies salient values and interprets a particular phenomenon to be risky or not. Relatedly, political ideology, which has been defined as the set of beliefs about the proper order of society, has a strong influence on political attitudes and behaviours and general value orientations - and, by extension, risk - in a pattern similar to what scholars find with Cultural Theory. The present study attempts to add to this body of research within the context of vaccination skepticism.

In order to test five hypotheses, detailed in the paper, the researchers rely on data from a nationally representative online survey, collected from January 25-27 2017. They found:

• Direct effects: Ideology has a strong and statistically significant effect on vaccination attitudes (B = -0.10; std. error: 0.03; p<0.01). More specifically, conservative respondents are less likely to indicate that they would vaccinate against pertussis, measles, and influenza than other individuals. Furthermore, both trust in health care provider (B = 0.27; std. error: 0.04; p<0.01) and trust in government medical experts (B = 0.19; std. error: 0.03; p<0.01) have direct effects on the dependent variable. For both variables, the path coefficient is positive and statistically significant, which suggests that people with faith in these two entities are also more likely to indicate that they would vaccinate if they missed the immunisation.
• Indirect effects: Ideology has a strong and statistically significant effect on trust in government medical experts (B = -0.18; std. error: 0.03; p<0.01). In particular, more conservative respondents tend to express lower levels of trust in institutions like the CDC than their less conservative counterparts. The estimated size of this indirect effect is -0.04 (std. error: 0.01; p<0.01). This amounts to about 29 percent of the total ideology effect on the dependent variable (B = -0.14; std. error: 0.03; p<0.01). "Strong conservatives" are thus estimated to score 0.56 points lower on the latent scale than "strong liberals". This means that the overall effect of ideology is not only statistically significant but also substantively meaningful. Contrary to the researchers' theoretical expectations, however, they find that an individual's political worldview does not seem to influence the extent to which they trust their family's primary health care provider (B = -0.02; std. error: 0.02; p<0.41).

These findings corroborate analyses that show that the intent to vaccinate differs among conservatives and liberals, with conservatives expressing less intent to vaccinate. Similarly, those with lower levels of trust in government medical experts are also less likely to express intent to vaccinate, and these individuals also tend to be conservative. What has been less understood in previous research, however, is the nature of the relationship between ideology and trust. The findings suggest that ideology has two routes in affecting people's vaccination attitude. One is direct, independent of trust. The other route goes through trust. That is, a person's ideology impacts whom they trust, such that they can selectively credit information related to vaccine risks and benefits in ways that reflect their ideology. This paper has thus established a direction in the relationship between ideology and trust, namely from ideology to trust.

This suggests that the success of knowledge-deficit strategies will be limited by whether individuals trust the sources by which they are informed of risks and benefits, where this trust in turn can be limited by ideology. These results and conclusions are consistent with earlier work by Rabinowitz et al. indicating that in the domain of vaccination choice (in addition to other domains), the perception of facts and beliefs, particularly perceptions of social norms, can differ between conservatives, moderates, and liberals. "Thus, to better gauge expected success of vaccine campaigns, attention should be given to socio-political context, and where possible, measures should be taken to tailor messages appropriately."