Green Party candidate Jill Stein likes to present herself as a pro-science, more idealistic alternative to Hillary Clinton. But a series of troubling comments by Stein are now making headlines for all the wrong reasons.

One of Stein’s most problematic opinions resurfaced this week. In response to a question about her stance on vaccines, she first claimed that there is “no evidence that autism is caused by vaccines.” But troublingly, her campaign reportedly deleted that tweet and replaced it with a more qualified and tentative answer: “I’m not aware of evidence linking autism with vaccines.” Although she hasn’t gone quite as far as Donald Trump—the Republican nominee has openly suggested that vaccines cause autism—Stein’s statements are at best misinformed. (They are also baffling given that the Green Party likes to tout its pro-science credentials.)

Stein claimed vaccine “regulatory agencies are routinely packed with corporate lobbyists and CEOs.”

In some ways, Stein’s comments are more insidious than Trump’s. At least Trump has made his position clear. During a Reddit AMA in May, Stein claimed that she distrusted vaccines because “regulatory agencies are routinely packed with corporate lobbyists and CEOs. So the foxes are guarding the chicken coop as usual in the US. So who wouldn’t be skeptical?” This line is blatantly misleading. As Stein (who is herself a medical doctor) ought to know, most of the people who sit on the Vaccines and Related Biological Products Advisory Committee are scientists and public health experts. Nevertheless, she reiterated this statement during a July 29 interview with the Washington Post, arguing that although “vaccines are an invaluable medication” they need to be “approved by a regulatory board that people can trust.”

She later added that when she was a medical doctor, “there were concerns among physicians about what the vaccination schedule meant, the toxic substances like mercury which used to be rampant in vaccines. There were real questions that needed to be addressed. I think some of them at least have been addressed. I don’t know if all of them have been addressed.”

In fact, researchers have spent a long time answering the “questions” Stein mentions.

The problem here is that in fact, researchers have spent a long time answering the “questions” Stein mentions. The academic article that helped spark the most recent iteration of the anti-vaxxer movement in 1998 has been conclusively discredited, and 10 of the paper’s 12 co-authors have since retracted their support. Subsequent studies have repeatedly found no correlation between vaccines and autism, and have confined that vaccines given to adults and children are safe with rare exceptions.

Similarly, there is no evidence that the recommended schedule of vaccines can cause other diseases later in childhood or that vaccines overwhelm a baby’s immune system. Although there is evidence that the MMR and MMRV shots have been linked to febrile (fever-caused) seizures, the episodes do not cause any long-term health effects. More importantly, such seizure are twice as likely to happen if a child’s vaccination schedule is delayed.

The academic article that helped spark the modern anti-vaxxer movement has been conclusively discredited.

What is clear, however, is the anti-vaccine movement’s consequences. Unvaccinated children have caused outbreaks of diseases that would have otherwise been preventable, including the mumps and whooping cough. An unvaccinated child was also tied to the worst US measles epidemic in twenty years. “A substantial proportion of the US measles cases in the era after elimination were intentionally unvaccinated,” wrote researchers at Emory University and Johns Hopkins Bloomberg School of Health earlier in 2016. “The phenomenon of vaccine refusal was associated with an increased risk for measles among people who refuse vaccines and among fully vaccinated individuals. Although pertussis resurgence has been attributed to waning immunity and other factors, vaccine refusal was still associated with an increased risk for pertussis in some populations.”

And then there’s the anti-vaccine movement offensive undertones. As a person with Asperger’s Syndrome who has written extensively about our culture’s evolving attitudes toward autism, I am deeply disturbed by the ease with which spectrum personalities are dismissed and belittled by anti-vaxxers. One of the main goals of the socially active autistic community is to explain why having the high-functioning version of this condition, as millions of Americans do, is not a disability, nor is it inherently debilitating. While social intolerance toward non-neurotypical behaviors can make life difficult for autistic people, high-functioning autism itself is neither healthy nor unhealthy. It is simply a difference in neurological structure.

In the future, the notion that high-functioning autistic people need to be “treated” or “prevented” will likely be viewed with the same contempt that we currently direct towards those who think you cure homosexuality. But so long as a large section of our population continue to view autism as a “disease” or a “glitch” ceased by corrupt doctors or medical boards, autism will remain stigmatized.

In light of the stakes involved here, Stein must unambiguously denounce the idea that vaccines cause autism. If she will not do this, she must admit that she is, in fact, aiding the anti-vaxxer conspiracy movement. Stein is running on a platform that champions economic and social injustice, and has told voters that she deserves to be taken just as seriously as her more mainstream rivals. Should she refuse to repudiate her vaccine comments, however, progressives need to accept the fact that their Green Party candidate may not be serious about contesting this election.