Conservatives are now the dominant anti-vaxxers

Historically, anti-vaxxers were a minority balanced across the political spectrum, but now conservatives are much worse

For the past few years, study after study has been showing a decrease in both conservative support for and rates of vaccination. This appears to be related to the current trend of conservatives toward an anti-science agenda in several countries and possibly the introduction of the human papilloma virus (HPV) vaccine.

Historically, the myth was that liberals were more likely to be anti-vaxx and conservatives were more likely to be pro-vaxx. It was seen, mostly by people on the right, as a hippie thing. The reality is that support of vaccination and rates of vaccination were equally spread across the spectrum. Until recently.

The most recent peer-reviewed study explicitly on the subject was published in January of 2018. The influence of political ideology and trust on willingness to vaccinate by Baumgaertner et al in PLOS One (open access, impact factor 3.54) has the following to say:

we asked respondents to place themselves on a five-point scale ranging from “very liberal” to “very conservative.” About 9.9 percent of respondents self-identified as “very liberal”, 17.5 percent as “liberal”, 41.4 percent as “moderate”, 21.6 percent as “conservative”, and 9.6 percent as “very conservative.” […] the overall effect of ideology is not only statistically significant but also substantively meaningful. […] Our 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.

A different study published in PLOS One (not finally peer-reviewed as of August 4, 2018, but already adjusted in minor ways due to review processes) in June 2018 which did not specifically ask questions pertaining to political belief nonetheless is illuminating. The state of the antivaccine movement in the United States: A focused examination of nonmedical exemptions in states and counties by Olive had some very interesting results. It was specifically an assessment of non-medical exemptions (NMEs) for vaccinations in the 18 states in the USA which permit them.

The first observation is that the states in question skew to conservative beliefs and the second is that the rate of NME is rising.

It’s also worth pointing out the top 10 counties for NMEs. All but one are in Idaho, a very red state.

It’s worth pointing out that the study found in general a strong rural-urban divide expressed as well, with rural areas tending to have greater percentage of NMEs. That rural-urban divide also maps onto conservative vs liberal likelihood as well, with rural areas much more likely to be conservative. However, the study points out the following concern:

Our findings indicate that new foci of antivaccine activities are being established in major metropolitan areas, rendering select cities vulnerable for vaccination-preventable diseases.

That bit led some journalists to try to make the case that vaccine rejection was balanced across the political spectrum, but that’s not what the data shows.

The last study to look at also reflects this increasing conservative discomfort for vaccination. Geospatial patterns of human papillomavirus vaccine uptake in Minnesota by Nelson et al, published in the British Medical Journal (BMJ) Open (peer-reviewed, impact factor 2.369) in 2015 found a strong correlation to conservative rejection of vaccination.

Prevalence of HPV vaccination was found to exhibit strong spatial dependence across ZIP codes. Accounting for spatial dependence, age (OR=0.76, 95% CI 0.70 to 0.83) and male gender (OR=0.04, 95% CI 0.03 to 0.07) were negatively associated with vaccination, while liberal political preferences (OR=4.31, 95% CI 2.32 to 8.01), and college education (OR=2.58, 95% CI 1.14 to 5.83) were found to be positively associated with HPV vaccination.

Once again, in addition to the clear finding of liberals in this study being much more strongly supportive of HPV vaccination, there are multiple signifiers of conservative mindsets with older men explicitly being much less likely to support vaccination.

The HPV vaccine is unlike other vaccines in that it is directly related to transmittable sexual diseases, a factor which conservatives have a much greater issue with. I haven’t seen published evidence for this, but I have a weak hypothesis that introduction of the HPV vaccine is leading to conservative rejection of vaccines in general.