For decades, Barbara Walters has been described as a broadcast pioneer—and with good reason. In 1974, Walters became the first female host of the “Today” show. In 1976, she became the first woman to serve as a network-news anchor. In 1984, she moderated the first Presidential debate between Walter Mondale and Ronald Reagan. Since then, she has interviewed everyone from Fidel Castro to Kim Kardashian. Her ABC talk show, “The View,” which she created in 1997, has received twenty-nine Daytime Emmy Awards and maintains an audience of three million viewers. Walters, who is eighty-three, will retire next year, but her impact on both her profession and her audience would be hard to overstate.

That’s why it is so distressing to add another first to the list of Walters’s achievements: Jenny McCarthy, who will join “The View” in September, will be the show’s first co-host whose dangerous views on childhood vaccination may—if only indirectly—have contributed to the sickness and death of people throughout the Western world. (See jennymccarthybodycount.com.) McCarthy, who is savvy, telegenic, and pulchritudinous, is also the person most visibly associated with the deadly and authoritatively discredited anti-vaccine movement in the United States. She is not subtle: McCarthy once essentially threatened the actress Amanda Peet, who has often spoken out about the obvious benefits of childhood vaccinations, by warning Peet that she had an angry mob on her side. When people disagree with her views on television, McCarthy has been known to refute scientific data by shouting “bullshit.”

It’s been fifteen years since Andrew Wakefield published an article in the medical journal the Lancet which connected the childhood measles, mumps, and rubella vaccine to autism. The article was eventually retracted; ten of the thirteen original contributors long ago withdrew their work; Wakefield was found guilty of “callous disregard” for the pain of children; and, despite scores of studies, involving tens of thousands of children in several countries, no association has been found between autism and vaccines of any kind, no matter when they are administered or how many a child receives. Yet, that paper set off a wave of fear that has helped convince thousands of people that vaccinations are dangerous. McCarthy has repeatedly asserted that the rate of autism has grown rapidly alongside the number of vaccines children receive, which is not true. It is understandable that people would suspect vaccines are a cause of autism; parents often first notice developmental problems when their children are about eighteen months old, the same time they often receive several vaccinations. Causation and correlation are often confused, however, as many studies have demonstrated. (Assuming that events that happen at the same time are connected can lead to serious misconceptions: over the last decade, for example the rise in sales of organic food in the United States has mirrored the growth in autism rates almost exactly. No sane person would suggest that those facts are related.) McCarthy doesn’t care; for her, facts are just another point of view. She became active in the anti-vaccine movement when she decided that her son became autistic after receiving a vaccine. The accuracy of his diagnosis has often been questioned; McCarthy now claims that her son was cured after being put on a gluten-free diet and subjected to chelation therapy, which extracts metals from the body. There has never been a verified scientific report that chelation therapy, a gluten-free diet, or anything else can cure autism.

McCarthy has spent much of the past ten years campaigning against vaccines—which, it must be said, are the most effective instruments of public health in human history, aside from clean water. That does not mean that vaccines carry no risk: nothing is entirely without risk, and there is a small but measurable possibility that any vaccine can cause a serious adverse reaction. Still, the benefits for society so powerfully outweigh the risks that suggesting otherwise is irresponsible at best. It spreads fear and incites the type of ignorance that makes people sick. That is exactly what McCarthy has been doing. By preaching her message of scientific illiteracy from one end of this country to the other, she has helped make it possible for people to turn away from rational thought. And that is deadly.

Executives at ABC should be ashamed of themselves for offering McCarthy a regular platform on which she can peddle denialism and fear to the parents of young children who may have legitimate questions about vaccine safety. Presumably, those executives have decided that the revenues Jenny McCarthy might generate are worth more than the truth. That’s their right. But it’s a strike against reason and progress and hope. That is a cost that the network won’t be able to afford for long, and neither will the rest of us.

Photograph by Donna Svennevik/ABC via Getty.

Correction: An earlier version incorrectly stated the year Barbara Walters became the first female network-news anchor.