THURSDAY FEBRUARY 07 2002

The MMR controversy

A lone doctor's fear set parents against experts

BY NIGEL HAWKES, HEALTH EDITOR

DOUBTS over MMR surfaced in the mid-1990s when Andrew Wakefield, of the Royal Free Hospital in London, published claims of a link between the measles vaccination and childhood illness.

Although it is autism that has moved centre stage, his first Lancet paper in 1995 linked the measles vaccine — not MMR — with an entirely different condition: the inflammatory bowel condition, Crohn’s disease.

The research team compared 3,500 people who had been given the measles vaccine in 1964 with 11,000 born in 1958 who were not vaccinated but had caught measles naturally. Analysis showed that the vaccinated group were three times more likely to develop Crohn’s disease.

Although widely reported, the claims did not start a scare. Two years later Dr Wakefield published a second study in The Lancet of 12 children who developed autism as well as a bowel condition soon after being given the MMR jab. By this time the team had decided that the bowel condition was not Crohn’s.

Such a small study could not prove cause-and-effect, and Dr Wakefield’s colleagues from the Royal Free made no such claim. He went further than the rest, saying that MMR should be abandoned until research could prove that it was safe. “In all conscience, I cannot support the idea of using all three vaccines together,” he told The Times in February 1998.

Parents anxious for an explanation as to why their children had developed autism seized on Dr Wakefield’s claims. Many other cases emerged of children who first showed symptoms soon after MMR vaccination, seeming to lend weight to the hypothesis. Other specialists’ reassurances that association does not equal causation had little effect.

The biological rationale for the claims was never very clear. Dr Wakefield at first suggested that the measles virus might damage the bowel, which would be unable to deal effectively with the opiates formed in the intestine from food such as milk and wheat. These could then get into the brain, affecting development. He also made a secondclaim: that administering three vaccines at once could overload the immune system.

Virtually no other expert who has examined the evidence believes the link stands up. It was reviewed in March 1998 by 37 experts called together by the Chief Medical Officer, Sir Kenneth Calman, who concluded that any link was purely coincidental. The first MMR jab is given at 16 months, almost exactly the time when autism symptoms first become apparent.

A big study in Finland, published in May 1998, also argued strongly against the claim. The researchers followed millions of children who had been given MMR between 1982 and 1996 and found no link to autism.

Since then a series of expert reviews have failed to support the Wakefield theory, or the claim that the three vaccines given independently would behave any differently from MMR. The Committee on Safety of Medicines reviewed the evidence cited by Dr Wakefield and concluded that it was “highly selective” and that it did not show that MMR had any higher rate of adverse events than the three vaccines given independently.

Despite these reassurances, the take-up of MMR has been in steady, if slow, decline since 1997. The pressure to offer single vaccines has grown.

The case against the single vaccines is that while there is no evidence that they are safer, there is evidence that giving the vaccinations separately is less effective. This is because it requires six injections instead of two, spread over a longer period, leaving children vulnerable for longer. Mothers having to take their children to and fro six times would also be less likely to complete the course.

Single vaccines would not necessarily be any more expensive although there would be increased costs for GPs’ time, and for chasing up patients to ensure that they completed their courses. It is efficacy, not cost, that is the real argument against single vaccinations. MMR take-up in the UK is 84.2 per cent, with some areas, including London, falling well below this.

For full protection, the World Health Organisation recommends 95 per cent uptake, but effective control can be achieved at lower levels than this.

Once it falls below 85 per cent the risk of outbreaks is a real one, because there are sufficient unvaccinated children to spread the infection.

DEBATE

MMR: choice or dilemma?

From Monday: debate the issues of the day at debate@thetimes.co.uk