The pertussis vaccine against whooping cough  (AFP/Getty Images)

For a long time, it has been apparent that skepticism about the science of climate change is not evenly distributed across the political spectrum. Rather, multiple studies have shown that it is more common on the political right.

But on other specific issues such as nuclear power or genetically modified food, distrust of science might be more of a liberal phenomenon and spring from a very different worldview. In particular, the issue of vaccine skepticism — where people decline recommended vaccinations because they doubt the medical community’s claims of safety and effectiveness — has often been associated with the political left. But is that really right?

Lawrence Hamilton, a sociologist at the Carsey School of Public Policy at the University of New Hampshire, found one way to examine this question in a study that has just appeared in SAGE Open, an open access social science journal.

“There’s been some discussion where commentators say ‘Well, okay, conservatives oppose science on the topic of climate change or evolution, but there are other topics where the bias goes in the opposite direction,’” says Hamilton, who undertook the study with a university colleague and another researcher from the University of Colorado at Boulder. “So what we did was we set out to test that.”

And Hamilton and colleagues found that at least in two U.S. regions, Republicans — and especially Tea Party supporters — were more distrusting of scientists not only on the subject of climate change, but also on vaccines.

The study is limited: The researchers only surveyed Americans in New Hampshire and northeastern Oregon. Residents of New Hampshire, a traditional swing state, tend to look a lot like the United States in general in their environmental views, the study notes. But northeast Oregon voters tilt conservative. More than 1,000 people were surveyed in each state.  

The study asked people about their political party affiliations, and then later, about their views on “the political movement known as the Tea Party.” Then they sorted them into four groups: Democrats, Independents, Republicans, and Tea Party supporters. The last were members of any of the three parties who said that they “support” the Tea Party, although of course, “the great majority” of the Tea Party supporters came from Republican ranks, Hamilton explains.

“So statistically, what you’re doing is distinguishing two types of Republicans,” he adds.

Then respondents were asked,

Would you say that you trust, don’t trust, or are unsure about scientists as a source of information about [vaccines/climate change]?

Here were the results.(Note that the study also asked the northeast Oregon residents about their trust in scientists on “forest management issues”; those data aren’t shown here.)

Trust in scientists in New Hampshire and northeastern Oregon on two scientific issues, broken down by political party affiliation and Tea Party support. (Credit: Lawrence Hamilton)

As you can see, while traditional Republicans and Tea Party supporters in these locations trust scientists considerably more on vaccines than they do on climate change, they also trust them on both issues considerably less than Democrats do.

“The vaccine results were something new, and what was unexpected there was that they followed a very similar pattern to climate change,” says Hamilton. He acknowledges that conducting the survey in two U.S. states is not the same as conducting a nationally representative survey. But he adds that finding a similar result in two quite different parts of the U.S. represents “a fairly broad replication.”

The results parallel prior research that has suggested that vaccine skepticism is not an exclusively liberal phenomenon and may even be slightly more prevalent on the political right. However, the new study appears to find a considerably bigger rightward political tilt to vaccine skepticism than this past research does.

For Hamilton, the reason for this is that he’s asking not just about vaccines, but about trust in scientists about vaccines. Thus, the results likely reflect skepticism not only of vaccines but of the scientific community, which has often been criticized by conservatives for its well-documented political liberalism.

The study also found something else — what researchers term an “interaction effect,” involving how political party affiliation interacts with levels of education to shape views about scientific issues.

In general, as Democrats and Independents increased in their level of education, their trust in scientists on climate change and on vaccines tended to increase. But this was not always the case for those of different political persuasions. In particular, the study found that “trust in scientists on each topic rises steeply with education among Democrats and Independents, and rises less steeply or not at all with education among Tea Party supporters.”

Why would that be? The researchers speculate that those with higher levels of education — in any political camp — may be more prone to “more effective and motivated acquisition of information. With respect to vaccines, this might, depending on one’s prejudices, go in one direction toward greater awareness of medical studies and advice or in the opposite direction toward anti-vaccination sources.”

Such an interaction effect — in which liberals or Democrats become more trusting or accepting of science with more education, while conservatives either do not, or even do the opposite — has also been observed on the climate issue. Indeed, it showed up in Hamilton’s climate polling results for New Hampshire (but not as much for northeast Oregon).

Why would conservatives or Tea Party members be distrustful of vaccines? One possible reason is distrust of the government — the Centers for Disease Control champions vaccines — or of state-mandated vaccinations.

But as Hamilton notes, you could also postulate, in the abstract, that anti-vaccine views would more appeal to the political left because of “concern about chemicals and big corporations,” as the study puts it. “Before looking at the data, you could make the argument either way,” says Hamilton.

The data, however, further support the idea that when it comes to vaccines, doubt or rejection is hardly the exclusive province of the political left.