A new study published in the scientific journal PLOS One has found evidence that conservatives are less likely to want vaccinations because of their distrust of government institutions.

The findings suggest that current public health campaigns aimed at increasing vaccination rates could be ineffective.

“We became interested in the project because we all work on various aspects of how decision-making is affected by social and political factors such as trust, media, information source, echo chambers, and in this case, political ideology,” explained study author Bert Baumgaertner, an assistant professor at the University of Idaho, Moscow.

Previous research had found that liberals were significantly more likely than conservatives to report having fully vaccinated their children. But that study was based on a convenience sample of 367 U.S. adults.

The new study used a nationally representative online survey of more than 1,000 U.S. adults. The survey found that conservatives were less likely to say they would vaccinate against pertussis, measles, and influenza compared to liberals.

People who distrusted government medical experts were also less likely to vaccinate, and these individuals also tended to be conservative.

“There are strong differences between conservatives and liberals with regards to the degree to which they trust government medical experts (such as the Centers for Disease Control and Prevention, or CDC),” Baumgaertner told PsyPost.

“Furthermore, vaccination attitudes are strongly affected by ideology. Interestingly, we find that there is no difference between liberals and conservatives in terms of their trust in primary health care providers.”

The findings line up with another study published in 2015, which found that Republicans and independents were significantly less likely than Democrats to say they would get the H1N1 “swine flu” vaccine. That study indicated that confidence in government was a key factor in whether or not people decided to vaccinate.

Baumgaertner and his colleagues noted that current strategies used to promote vaccination often involve government entities warning the public about the risks of going unvaccinated. But such strategies could have limited impact if individuals don’t trust the sources of information.

“One thing that surprised us was that we did not see a substantial difference in vaccination attitudes between the low risk and high risk scenarios,” Baumgaertner added. “One might think this is because people don’t take into account risk in their decision making. The literature on decision making under risk suggests that people do take risk into account.”

“This leads us to believe that we failed to clearly distinguish between the two scenarios. In a follow-up survey we focus our efforts on understanding how differences in risk information affects people’s vaccination attitude (if at all).”

The study, “The influence of political ideology and trust on willingness to vaccinate“, was co-authored by Juliet E. Carlisle and Florian Justwan.