Andrew Wakefield's MMR vaccine theory has been discredited for years, but he just won't go away

Wakefield has portrayed himself as a campaigner on behalf of the children and desperate parents, but his attempt to colonise the moral high ground turned out to be a sham

Andrew Wakefield’s discredited 20-year campaign to link the MMR vaccine to autism has been sustained by a simple scientific fact: it is impossible to prove a negative.

If you want to show that X exists, you must design an experiment to show it, and others must be capable of repeating your experiment with the same result. If, however, you want to show that it does not exist, it does not matter how many times you carry out experiments showing that it does not, there is always the possibility that another attempt would reveal its existence after all.

After Wakefield made his controversial claim at the press conference to launch his 1998 paper in The Lancet, scores of researchers attempted to confirm his observations – without success. The scare nevertheless took hold and has been sustained through two decades since.

The possibility that the childhood vaccination programme was causing harm to children is one of the most emotive in medicine. Parents wondering whether to vaccinate their children have to make a leap of faith. Once undermined, that faith is extraordinarily hard to rebuild.

Throughout this time Wakefield has portrayed himself as a campaigner on behalf of the children brought to him by desperate parents searching for the cause of their offspring’s suffering. His suggestion that it might be linked with MMR vaccine chimed with parents’ deepest fears about the safety of exposing babies’ developing immune systems to potentially toxic drugs.

From the start he claimed to be driven by a passion to protect children. In an interview with me published in The Independent in 1998, he said: “If I am wrong, I will be a bad person because I will have raised this spectre. But I have to address the questions my patients put to me. My duty is to investigate their stories. It is a moral issue with me.”

But his attempt to colonise the moral high ground turned out to be a sham. It was revealed that he accepted payments from the Legal Aid Board (for his patients who were suing the vaccine manufacturers) in what The Lancet called a “fatal conflict of interest”, failed to disclose details of the way the patients were collected and, most importantly of all, conducted invasive and unpleasant investigations on vulnerable children which were of no benefit to them but only to his research.

He lost the scientific argument in 2004 when The Lancet announced a partial retraction of his 1998 paper (it was fully retracted in 2010 after the General Medical Council verdict). He lost the moral argument in 2010, when he was found guilty of gross professional misconduct by the GMC and struck off the medical register. Yet he remains defiant.

The MMR vaccine has been available in the US since 1963, and the US believed it had eliminated measles more than a decade ago. That meant any cases occurring in the country would have been imported from abroad, and there was little or no danger of domestic transmission. But in 2015 an outbreak in southern California that started at Disneyland rapidly spread to infect more than 50 people.

The Los Angeles Times reported that the percentage of nursery schools where fewer than 92 per cent of children were fully vaccinated had more than doubled between 2007 and 2014.

Medicine needs its mavericks. The history of scientific advance is littered with individuals who held out against major political and commercial interests. Think of smoking and cancer – a link that took decades to establish against the carefully orchestrated obfuscations of the tobacco industry.

But these brave and gifted individuals are hugely outnumbered by those who believed they were on to something and whose hypotheses later died. The problem for Wakefield is that although a handful of studies appeared to offer him support, scores failed to do so.

Every major medical organisation believes there is no safety issue over the MMR vaccine. His research has been discredited; he lost his job in the NHS; his licence to practise medicine was withdrawn and his reputation is in tatters. Yet still he criss-crosses America – and the world – spreading his baleful messages.