Thirteen years ago, British gastroenterologist Andrew Wakefield published a research study in The Lancet that triggered one of the biggest health scares of modern times. He claimed he had found a link between a common childhood vaccine and autism. The evidence was sketchy – it was based on just a handful of children – but the impact was explosive. Anti-vaccination panic soon infected both Britain and North America. Media celebrity Jenny McCarthy published several bestsellers claiming that the MMR (measles, mumps, rubella) vaccine had given her son autism. Robert F. Kennedy Jr. accused the government of a giant cover-up.

But mountains of further studies failed to turn up any evidence that vaccines are linked to autism. Dr. Wakefield, it turned out, had taken large amounts of money from a personal-injury lawyer who was suing pharmaceutical companies over the vaccine. Last year, The Lancet retracted the study. And now a damning series of articles in the British Medical Journal has shown that his research was fraudulent.

Even so, true believers are standing firm. After the CBC's The Current aired the Wakefield scandal, angry listeners called in to insist that Dr. Wakefield is being made a scapegoat for telling the truth.

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Anti-vaxers are not uneducated types. In fact, the vaccination panic is strongest among highly educated liberal elites – the same demographic that votes green, drives a Prius and eats organic. "It's the graduate-school-educated, college-educated people who tend not to vaccinate," says Paul Offit, chief of infectious diseases at the Children's Hospital of Philadelphia.

And who can blame them? The public is fed a steady diet of scare stories cooked up by rogue scientists seeking publicity, tort lawyers looking for a payday, environmental groups hungry for both publicity and funding, and gullible media ever eager for a good bad story. The "expert" journals share the blame. The Lancet sent Dr. Wakefield's study to six reviewers. Four of them rejected it. But it was sexy, so the medical journal published it anyway. The Lancet took more than a decade to admit the study was junk.

The vaccination panic fed off popular mistrust of Big Pharma, the biggest villain (after investment bankers) in today's popular culture. Ironically, anti-vaxers are usually hyper-parents – obsessively worried that the world is full of hidden poisons that can harm their kids. They worry about the sun, or lawn spray, or trace amounts of chemicals in plastic toys. They trust their intuition more than they trust the authorities, and they trust their friends most of all. And they reinforce each other on the Internet.

In his searing new book, The Panic Virus, journalist Seth Mnookin recalls a dinner party he attended in an upscale Brooklyn neighbourhood. He asked a first-time father why he and his wife had decided to delay giving their son some of his shots. "I don't know what to say," the father said. "It just feels like a lot for a developing immune system to deal with."

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In the U.S., the highest vaccination non-compliance rates are found in progressive enclaves such as Ashland, Ore., and California's Marin County – think Toronto's Beaches or Vancouver's West End. These are the same people, Mr. Mnookin notes, who are likely to have bumper stickers that ridicule creationists.

Most of us are amazed at the astonishing number of people who believe Barack Obama is a Muslim or the U.S. government has covered up flying saucer landings in New Mexico. The anti-scientism of large swaths of the affluent liberal class rarely gets the same attention. But it's probably done a lot more harm. The erosion of vaccination rates led to fresh outbreaks of childhood diseases that were nearly extinct. Measles made a comeback in England and Wales. Mumps broke out in New York and New Jersey. In Canada, vaccination fears have been blamed for the low uptake of flu shots. In California in 2009, 10 children died after being infected with whooping cough. It's a shame we no longer remember the bad old days, when measles killed and polio epidemics condemned children to iron lungs.

The anti-vaccination outbreak is not the first mass rejection of science among the educated classes. In the 1990s, North America was gripped by panic over child sex abuse. Hundreds of innocent parents and daycare workers were suspected, charged and even convicted of fantastical sexual abuse of children. Meantime, tens of thousands of women were encouraged to "recover" repressed memories of early childhood abuse in therapy. Newspapers published uncritical accounts of this shocking social scourge and quoted "experts" to support it. Families split apart. Many of the smartest people in society ardently believed in the theory of repressed memory until, eventually, the evidence – or, rather, lack of it – proved too strong to deny.

Scares like these die slowly. According to a new Harris poll, 18 per cent of Americans remain convinced that vaccines can cause autism. Another 30 per cent aren't sure. Only 52 per cent believe the association isn't real. (The good news is that only 20 per cent of Americans think Mr. Obama is a Muslim.)

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"Low vaccination rates threaten the immunity of whole communities," warns Mr. Mnookin. "If only there were a shot for irrational fears."