Republicans are more skeptical of vaccine science than we may have previously realized—and Donald Trump may bear some of the blame.

A new study, conducted for The Daily Beast by a researcher at Washington State University, found a relationship between Republican party affiliation and anti-vaccine sentiment. Survey participants who didn’t plan to vaccinate themselves or their families most often named Donald Trump as a public figure they thought shared their views.

Anti-vaccine sentiment was also disturbingly high among Democrats who participated in the study, though not as prevalent as among Republicans.

Donald Trump, the presumptive Republican nominee, has expressed significant skepticism about vaccine science over the years, even going so far as to suggest vaccines cause autism. As a result, he’s become a hero to many in the anti-vaxx movement—the rare public figure willing to champion their dangerous and incorrect beliefs.

The new data runs counter to the prevailing public view on the relationship between political affiliation and vaccine skepticism—that there is little to no relationship—and suggests that Trump’s ascent in the Republican Party is related to doubts about vaccines among its members.

Researchers ran an internet survey of 400 people in the United States on June 29 using Amazon’s Mechanical Turk. It’s a tool academics commonly use to survey large numbers of people, including those researching political psychology, consumer behavior, and social psychology. Participants answered one series of questions on their intentions to vaccinate themselves and their families, and another on their political views. Half the participants got the vaccine questions first, and the other half got the political questions first. After answering those questions, participants were asked to name public figures who they thought shared their views on vaccines.

SUNY-Albany marketing professor Ioannis Kareklas and Washington State University Ph.D. candidate T.J. Weber analyzed the data. They found that 25 percent of respondents affiliated with the Republican Party said it was more likely they would not vaccinate themselves and their families than that they would. Meanwhile, 15 percent of respondents who identified with the Democratic Party gave the same answer.

And Trump’s supporters were substantially more likely to have a negative view of vaccines than Hillary Clinton’s. Of the respondents who said they would vote Trump, 23 percent said they were unlikely to get vaccinated. Of the pro-Clinton respondents, 13.5 percent felt the same way.

Overall, researchers found that having a low intention to vaccinate correlated most strongly with affiliation with the GOP.

The follow-up questions also provided interesting answers. The respondents who gave positive answers about vaccines most often listed Barack and Michelle Obama as the public figures who agreed with them.

Pro-vaccine respondents also said Bill and Hillary Clinton and Ted Cruz shared their views.

Of the respondents who were negative about vaccines, Trump’s name got mentioned the most; 12 percent of vaccine skeptics said they thought he shared their views. No other anti-vaxx celebrity got named as often as Trump.

Jonah Berger, a professor of marketing at the Wharton School at the University of Pennsylvania and the author of “Contagious: Why Things Catch On,” said the results were “interesting, and consistent with the notion that conservatives in general, and trump voters more specifically, are less likely to vaccinate.”

Trump’s rapid rise in conservative politics has given credence to the theory that Republican voters may be less disturbed by vaccine skepticism than their Democrat counterparts. But currently available evidence didn’t seem to undergird that theory.

Previous studies haven’t found a correlation between political affiliation and anti-vaccine views. In February of last year, 538.com downplayed any partisan divide on vaccines, calling it “relatively small.” That piece noted that Pew data found the inter-party gap grew slightly from 2009 to 2014. And a Huffington Post/YouGov poll conducted Feb. 2-4 2015 found only a “modest ideological divide,” and found only 1 percentage point difference between the percent of Republicans and of Democrats who believed the science on vaccines is beyond debate. That’s very different from our data, which suggests Republicans are more likely than Democrats to harbor skeptical views of vaccines.

Correlation isn’t causation, of course. And causal links are notoriously hard to prove. But this data suggests that a growing percentage of Republicans may be disinclined to vaccinate themselves and their family members, and may hold negative attitudes about vaccination.

Again, causal links are tough to prove. But the past year has seen one of the country’s most notorious vaccine skeptics ascent to the top of the Republican ranks. Donald Trump has long expressed doubt about settled science on vaccines. On March 30, 2012, he sent out a tweet indicating he believes there is a link between vaccines and autism—a view that is 100 percent false.

And he tweeted on Oct. 22, 2012 that Obama needs to “do something about doctor-inflicted autism,” another anti-vax trope with no basis in reality. And at the CNN debate on Sept. 16, 2015, he shared his baseless views with an audience of millions.

“We’ve had so many instances... a child went to have the vaccine, got very, very sick, and now is autistic,” he said at the time. “Autism has become an epidemic. It has gotten totally out of control.”

And Ben Carson, the only real doctor participating in the debate, condoned Trump’s trutherism.

“We have extremely well documented proof that there’s no autism associated with vaccinations,” he told the debate moderators. “But it is true that we’re giving way too many in too short a period of time. And a lot of pediatricians now recognize that, and they’re cutting down on the number and the proximity.”

There is no scientific evidence that giving babies multiple vaccines at once has any adverse health effects. Zero. Nada. Zilch. But that didn’t stop Carson and Trump from peddling fact-free claptrap to CNN’s massive audience.

Our new data suggests that their words may be having influence—and in a chilling way.