Laurie Wang

Adolescents in states that voted Democratic in 2012 are more likely to be vaccinated against human papillomavirus and other diseases than those living in red states, a new Yale study finds.

A team of researchers from the Yale School of Public Health have identified a notable association between state political voting patterns and the percentage of a population that has received a certain vaccine. In their analysis, the researchers examined polling data from the 2012 presidential election and vaccination coverage statistics for the HPV, tetanus-containing (Tdap) and meningococcal (MCV4) vaccinations from the 2012 National Immunization Survey-Teen. With this new knowledge, public health officials can more effectively promote vaccination for adolescents, according to the researchers.

The study, which was published in the American Journal of Public Health last month, concluded that parents in red states are much less likely to vaccinate their children against HPV. Most importantly, researchers said, these differences in vaccination coverage persisted even when the effects of variables such as demographics, health-care access and vaccination policy were excluded from the analysis. This implies there is a direct association between voting patterns and vaccination coverage.

According to the study’s lead author, emergency medicine and health policy professor Steven Bernstein, the team initially hypothesized that differences in HPV vaccination coverage would exist due to the “misplaced fear” that vaccinating against HPV — a sexually transmitted infection that accounts for nearly all cervical cancers — encourages earlier sexual behavior among girls.

While their data supported their hypothesis, the researchers were surprised to find that parents in blue states were also more likely to vaccinate their children against Tdap and MCV4 than parents in red states. Tetanus and meningococcal disease are bacterial infections that are not sexually transmitted. Researchers said they chose to study these three vaccines because they are all currently recommended for routine use in adolescents aged 11 to 12. While Tdap and MCV4 have much higher immunization rates than the HPV vaccine, all three vaccines still have significantly lower rates in red states.

“What was striking in this research was that for other vaccines that don’t necessarily carry the stigma and controversy associated with HPV, we saw that same pattern: Blue states have significantly higher rates,” said professor of public health Jason Schwartz, another co-author of the study.

From these results, the group concluded that the association between vaccination coverage and state voting patterns is not merely limited to the HPV vaccine. This suggests that there may be a “complex mix of psychological, sociocultural and political factors that drive decisions about immunizations,” according to the paper.

For these researchers, the next step is to focus on better understanding the associations between voting behavior and vaccination coverage. Currently, the extent to which certain factors — such as social values, trust in science and beliefs in the role of government — contribute to differences in vaccination coverage is unclear, said senior author Linda Niccolai, professor of epidemiology. She added that knowing more about the reasons for the differences in vaccination coverage could help guide programs to increase vaccine acceptance.

“We have the quantitative data, but we don’t have the qualitative data that would help us understand the reasons and beliefs that kids are undervaccinated. That’s what missing from this study,” Bernstein said.

When it comes to promoting vaccination, Niccolai said that emphasizing the effectiveness of vaccines and their strong safety records is “critical.” For the HPV vaccine, one way to do this is to focus the vaccine’s ability to prevent six types of cancer, she said. This way, rather than minimizing the concerns of some socially conservative groups, public health officials can instead place these concerns in the context of the HPV vaccine’s benefits, Schwartz added.

According to pediatrics and epidemiology professor Eugene Shapiro, who researches the effectiveness of vaccines and was not affiliated with the study, creating vaccine promotion strategies specific to certain localities could be helpful for areas that seem to be more resistant to adolescent vaccinations. Another possibility for future research involves looking for statistically significant patterns in vaccine coverage for other age groups.

“We might think about childhood vaccination, which is at times controversial and every bit as important to pediatric health and disease control,” Schwartz said. “It would be interesting to see if a similar pattern exists in voting patterns and coverage rates for vaccines given to infants and young children.”

As of Aug. 26, six out of every 10 girls and five out of every 10 boys in the United States have started the HPV vaccine series, according to the Centers for Disease Control and Prevention.