Doctors who studied children born before and after the introduction of the MMR vaccine concluded yesterday there was no evidence the jab caused autism or bowel problems.
Professor Brent Taylor, a consultant paediatrician at London's Royal Free hospital, said the results demolished the hypothesis of the consultant Dr Andrew Wakefield, whose research cast doubt on the safety of the combined mumps, measles and rubella jab.
"This must be close to the endgame for the belief, which has not been based on proper science, that MMR is the cause of autism or a sub-group of autism," Professor Taylor said.
The results came as Downing Street heightened its campaign to convince parents that MMR was safe by issuing a 13-page document spelling out its benefits.
But there were further signs of a decline in the uptake of MMR. The Medicines Control Agency (MCA) reported a nine-fold increase in use of the single measles vaccine last year.
As the argument continued, the British Medical Journal published the study by the Royal Free, the hospital where Dr Wakefield first made his claims before he was sacked last year. Researchers looked at the medical records of 473 autistic children born between 1979 and 1998 so that they could compare youngsters born before and after the introduction of the MMR, in 1988.
They found no change in the proportion of children with bowel disorders and regression across the 20-year period. Professor Taylor said that if MMR was linked to the onset of autism and gut problems in children, there should have been an increase after 1988.
The team also compared children who were vaccinated before signs of autism became apparent with those who were immunised after concerns about their development had been raised, as well as children who did not receive the jab.
But there were no differences in the rates of bowel disorders and regression across the three sets of children.
Professor Taylor, who has published three extensive research papers on the subject, said: "By any reasonable perspective, MMR is not involved. There is no evidence that MMR causes or triggers autism."
Dr Wakefield was unrepentant last night about having raised the alarm. "The doctors, the gurus, the aficionados are treating the public as though they are some kind of moronic mass who cannot make an informed decision," he told Channel 4 News.
Downing Street said its dossier aimed to give a fairer hearing to what it described as the overwhelming scientific evidence in favour MMR. Tony Blair, who was quoted extensively, told parents that it was their responsibility to protect their children's health and that the combined injection was the best way of doing this.
Health officials admit that in the past two weeks they have "become concerned" about the fall in MMR vaccination take-up. MCA figures suggest that parents have been worried about the risks for some time. About 13,000 doses of the measles vaccine and 24,000 single mumps vaccines were imported last year.
Corresponding annual figures were not available for 2000. But monthly figures suggest that an average of 1,053 doses of the single measles vaccine were imported last year compared with 116 the previous year. In the same period, the take-up of MMR fell from a national average of 88 per cent to 84.2 per cent.Reuse content