I knew that Oprah Winfrey was prone to antiscience; she has all sorts of New Age nonsense on her show, and the one time Randi was on in recent years he found the experience frustrating; Oprah unabashedly promotes all kinds of superstitious garbage. But now she's gone way, way too far: she's signed Jenny McCarthy -- notorious for her misleading statements about vaccines and autism -- on for a multi-platform deal. McCarthy has advocated a link between autism and vaccinations for years. She has written and spoken about it at length in very large venues like Oprah's and Larry King's shows, but her claims are wrong. Worse, they're dangerous: by claiming vaccines are dangerous, she is scaring parents into delaying or even preventing their children from being vaccinated. I don't think this threat to the health of our children can be overstated: we have already seen a dramatic rise in outbreaks in preventable diseases due to the rise in media presence of antivax claptrap, and there have been deaths of children, deaths of babies, because of it. And now Oprah is giving the premier mouthpiece for this movement a huge loudspeaker. The timing of this couldn't be more ironic, with Australian TV slamming the antivax movement due to the death of a four-week-old infant girl from whooping cough -- a death directly related to the antivaxxers in Australia -- with a growing response online to the distortions and outright lies of the antivaxxers here in the U.S, and with antiscience knee-jerking exacerbating the global reaction to swine flu. Oprah: you have screwed up on this one, and in a huge, huge way. Jenny McCarthy has loudly and publicly increased fears over vaccinations based on nonsense and bad science. By giving her a platform, you are virtually guaranteeing that vaccination rates will decline further, there will be more outbreaks of easily preventable diseases, and therefore we'll see an increase in deaths of children all around the world. You have claimed to want to make the world a better place -- and you have actually done so in many ways -- but this one act will completely negate any good you've done in the past. Antivaccination rhetoric kills. It is that simple.