Last week there was a bust-up in blogland. I'll explain later why it matters, but for now I'll just give you the bones of it. On one side was the author of the Bad Science blog, Ben Goldacre, who is an invaluable persecutor of the anti-scientific and wilfully inexpert.

On the other side was the warm, friendly broadcaster, Jeni Barnett, whose most substantial incarnation currently takes place on afternoons on LBC, a London local radio station, where she hosts a phone-in.

Goldacre was so annoyed about the January 7 edition of Barnett's show, dealing, among other things, with MMR and vaccination, that he posted the whole of it as a clip on his own website, where it acted as a sort of audio chamber of horrors to appal his readers. A few days later the lawyers for LBC contacted Goldacre and told him that he was infringing their copyright and must remove the clip forthwith, or else.

Goldacre was now anger squared. “This is not about LBC or Jeni Barnett,” he wrote. “This is about one perfect, instructive, illustrative example of a whole genre of irresponsible journalism that drove the media's anti-vaccine campaign for ten solid years, with serious consequences for public health.”

Goldacre's accusation is important. Last week ended with new figures for measles cases in the United Kingdom, showing that over the past decade we have managed the interesting - and almost unprecedented - trick of reintroducing into this country a disease that had more or less disappeared. A few children will have died as a result and some others will suffer serious long-term health problems. These figures correlate to the drop in parents giving their children the MMR vaccination. And that drop, more controversially, may be seen as the consequence of a panic about MMR that began around 2001, peaked in 2002-03, and still - even after the discrediting of the claims about the supposed link between MMR and autism affects vaccination rates today.

Unable to listen to the withdrawn audio clips, I settled for some of the transcripts of Barnett's phone-in as posted on various websites. The host had begun telling listeners: “Always at the back of it [vaccination] in my head is ‘hold on a minute, there's a drug company that's making lots of money out of it'.” She reminded listeners (in case they had overlooked it) that “if, as a human being you decide you do not want to give your child a vaccination, you should, in a democracy, have that right to say ‘no'.”

Of course they do have that right, which is why we're suffering measles outbreaks now. But it was more than that for Barnett, concerned as she was to bolster the position of those brave parents who refused to vaccinate. “It's a lonely decision, if you're not part of the herd, if you're not mooing with the other cows or baaing with the other sheep...” And so it went on.

The third element to today's argument is provided by a spread in The Sunday Times last weekend, providing new evidence about how the original scare story over MMR was created. It claimed that several of the 12 children who were the subjects of Dr Andrew Wakefield's original research paper in 1998 - the one on which virtually the entire MMR scare was founded - either had symptoms that predated their vaccination, or that developed several months afterwards. It also reminded readers that before the examination of any of these children Wakefield was already employed by a lawyer for the anti-vaccination pressure group, Jabs, to establish a case against the manufacturers of vaccines. One month before the first child in the study arrived at Wakefield's hospital, Wakefield had already filed a confidential document stating that the object of his research was to discover evidence “acceptable in a court of law” of a link between MMR vaccines and “certain conditions” reported by families seeking compensation.

And sure enough Wakefield did “discover” a link (though not one ever “acceptable in a court of law”). That research was never replicated by any other study and no correlation has ever been found between the incidence of autism and the use of MMR, despite Wakefield's constant and confident assertions that such definitive evidence was imminent.

But, oh Lord, who'd have believed it? It was the way in which Wakefield's lone thesis was reported, dramatised and discussed that created the MMR scare and, therefore, the current measles outbreaks.

Last week, justifying herself on her blog, Barnett invoked the spirit of the insurgent ignoramus. Yes, she said, she should have been ready with facts and figures on MMR. “As a responsible broadcaster I should have been better prepared; as a parent, however, I can fight my corner.” Then she added: “I don't know everything that goes into cigarettes but I do know they are harmful.”

But how did Barnett “know” they were harmful? Wasn't it down to the huge body of evidence showing the correlation between lung cancer and smoking? And didn't she recall the early days of that discussion, when anti-herd people would pause before lighting up and tell of elderly relatives who'd smoked all their lives without coming to harm? The shamefulness of much of the reporting of MMR by some journalists is the subject of much longer studies than I have space for.

What I find just as interesting is the psychology. And here's my fourth element. Last week a relative became involved in a multi-person e-mail exchange concerning vaccination against the virus that causes cervical cancer. The first query had hardly been lodged before one correspondent - a highly educated and intelligent woman - asserted that “girls have died in the US” from the vaccination, and implying that profit-seeking drug companies (with the connivance of governments, presumably) were prepared to kill our kids in order to make money.

This reply, though intended for limited circulation, was so categorical yet so paranoid, that it was easy to imagine a fresh scare, perhaps arriving later in the year, concerning these new vaccinations. Maybe there'd be a maverick doctor, maybe Juliet Stevenson would portray a bereft but instinctual mother in a docudrama, maybe hacks would fill their pages and phone-in hosts their long hours with speculation dressed up as information.

That's why I'm passionately for Goldacre, and why I find myself wondering whether we can file a class action against LBC for permitting a presenter to inflict her preposterous prejudices on her listeners, to the detriment of someone else's kids.

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