Children with autism do not react differently to other youngsters to the MMR jab, a study shows.
The jab has been highly controversial
London's Guy's and St Thomas's Hospital found no difference in the immune response to the jab in a study of 240 children aged between 10 and 12.
Fears about a link between the two were first raised in 1998, prompting a drop in uptake of the vaccine, but that research has now been discredited.
Studies since have shown there is no link and that has been confirmed again.
The research, partly funded by the Department of Health and published in the Archives of Disease in Childhood, is the largest of its kind.
Previous studies have mainly looked for a possible link by examining autism trends in large groups of populations.
But the Guy's and St Thomas's team analysed blood samples of 240 children aged 10 to 12 to see if the MMR jab had caused an abnormal immune response that could have triggered autism.
This would have been indicated by increased antibody levels, but the researchers found no difference in the three groups they studied - children with autism, those without and those with special educational needs.
While all the children had had the first MMR jab, not all of them went on to have the second needed for maximum immunity.
The children who developed autism or special educational needs were the most likely not to have had the follow up jab - an indication of the public suspicion surrounding the safety of MMR.
Researcher Dr David Brown said: "The study found no evidence linking MMR to autistic spectrum disorder and the paper adds to the overwhelming body of evidence from around the world supporting the use of MMR."
The Lancet medical journal published research by Dr Andrew Wakefield which led to the possibility being raised of a link between the jab and the condition in 1998.
The journal subsequently distanced itself from the study of 12 children after it emerged Dr Wakefield had received funding to support legal action by a group of parents who claimed their children were damaged by the vaccine.
Dr Andrew Wakefield is currently appearing before the General Medical Council on charges relating to the claims.
But all this was after the publication had had an impact. The up-take of the triple-jab slumped in the immediate aftermath and is still under the 95% needed for herd immunity in some places, particularly London.
The number of confirmed measles cases has risen from 56 in 1998 in England and Wales to just under 1,000 in 2007, according to provisional data.
However, the impact of MMR on these figures is not clear.
Professor David Salisbury, director of immunisation at the Department of Health, said: "It's natural for parents to worry about the health and well-being of their children and I hope that this study will reassure them that there is no evidence linking the MMR vaccine to autism."
But Jackie Fletcher, from Jabs campaign group, said the conclusions were misleading.
"It is making a leap from having the actual data on the antibodies and saying MMR does not cause autism."