A measles outbreak in B.C.'s Fraser Valley has spread into the general population, beyond the Chilliwack Christian school where it is thought to have started. There's one important component missing from that sentence: I should have said, "an entirely preventable measles outbreak." Like recent outbreaks in Alberta and Quebec, there is no reason why this should have happened, except that people are refusing to have their children vaccinated – and thus putting other people at risk.

Vaccination rates have fallen in many industrialized countries over the past 15 years for no good reason, and many bad ones. You need only look at the Council on Foreign Relations map showing thousands of recent cases of entirely preventable diseases – measles, mumps, whooping cough – in places where vaccines are free, safe and readily available. Parents in Syria will brave bombs and gunfire to have their kids vaccinated – what excuses do parents in Western Europe and North America have?

In hyper-health conscious New York, there's been another recent outbreak of measles, which caused Russell Saunders, a doctor writing under a pen name in The Daily Beast, to write an understandably angry piece: "Just over a dozen years ago this illness was considered eliminated in our country, and this year people are being hospitalized for it. All due to the hysteria about a safe, effective vaccine. All based on nothing." He points out that measles is not an easily dismissed virus: It can lead to severe complications, and in three cases out of 1,000, death.

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But this misplaced hysteria has to be based on something, right? Why would otherwise rational parents, who wouldn't dream of driving their kids unbuckled and out of their car seats, risk their health – and the health of their classmates – by not having them immunized?

Why do so many people, despite evidence to the contrary, still believe vaccinations are unsafe? (Canada's immunization rate is reported to be 84 per cent; in parts of Southern Alberta, where there was a measles outbreak last year, it's as low as 60 per cent.)

You can blame it partly on the infamous, now discredited 1998 study that linked the measles, mumps and rubella vaccine to autism. But that's only part of the story. As Seth Mnookin writes in his excellent book about vaccination, The Panic Virus, otherwise well-educated, well-off, health-conscious parents are making deeply illogical decisions based on little more than a hunch and a whizz through Google. "When it comes to decisions around emotionally charged topics, logic often takes a back seat to what are called cognitive biases – essentially a set of unconscious mechanisms that convince us that it is our feelings about a situation and not the facts that represent the truth."

A new study in the journal Pediatrics reinforces that exact point. A survey of almost 2,000 U.S. parents found that pro-vaccination messages were unpersuasive for those who already had doubts about immunization. In some cases, the pictures and stories of sick children, whose illnesses could have been prevented, actually reinforced their unfounded beliefs that vaccines were dangerous.

Reading between the lines, you can almost feel the researchers throwing up their hands. How do you deal with such intransigence? The Pediatrics team recommended that governments' pro-vaccination messages should be better crafted, and that pediatricians, whom parents trust, should have a more central role in campaigns.

There are other methods of persuasion, some more carrot than stick. Australia, aiming for a 100-per-cent vaccination rate, announced plans to claw back tax breaks for parents who won't immunize. Dr. Saunders, who I mentioned earlier, has written that his practice won't accept patients if their parents aren't having them vaccinated. This may seem drastic, but he writes that he has to think of the health of his other patients.

These are all fine if you believe in the "nudge" theory of influencing behaviour, but in this case, I'd argue we need more of a good old kick in the pants. If we penalize people for other behaviour that's harmful to the public good – smoking in bars, not using car seats – then why would we not fine them for refusing to vaccinate their children? Under the law, you are not allowed to physically abuse your children – why should you be allowed to willfully expose them and others to easily prevented harm?

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This would not be politically palatable, I'm sure, but then neither is the alternative: a bunch of kids who are sick and didn't have to be.