A major new British study provides further evidence against a link between the MMR vaccine and the onset of autism. It also discounts any connection between the MMR vaccine and bowel or developmental problems in children with autism. Dick Ahlstrom, Science Editor reports.
London-based teams from the Royal Free and University College Medical School and Britain's Public Health Laboratory Service conducted the research and published it yesterday on the British Medical Journal website at www.bmj.com
The study found no evidence for claims that there might be a "new variant" form of autism with symptoms of "regression" (any sign of developmental setback) and bowel problems triggered by the vaccine.
It is the latest piece of evidence against the involvement of the measles, mumps and rubella three-in-one vaccination in the incidence of autism, a serious developmental disorder. Autism often begins to emerge at about the time a child receives MMR vaccination, which has led to suggestions that the vaccine might be responsible.
The researchers identified 473 autistic children born between 1979 and 1988. The MMR vaccine was introduced in 1988 which, if the autism claim and suggestions of a new variant form were true, should mean an increase in autism cases with regression and bowel problems. However, the researchers found no increase.
"The results showed no evidence of an association with MMR vaccination, nor a change by year of birth in the proportion with these symptoms," the researchers said. "We found no change in the proportion of autistic children with bowel problems or developmental regression over a 20-year period from 1979, a period when MMR vaccination was introduced in the UK."
Health officials in Ireland and Britain have battled against concerns about autism because it has worked against the success of vaccination campaigns. MMR vaccination rates here have ranged between 60 and 70 per cent, but levels must reach about 95 per cent to provide good protection against major measles outbreaks. Measles causes death in one in 1,500 cases and can also cause deafness and other problems.
The researchers found "no significant difference" in the rates of bowel problems or regression among three groupings of autistic children. These included children who received the MMR before their parents became concerned about their development (where MMR might have caused the autism); children who received it only after such concern was expressed; and autistic children who had not received the vaccine at all.
They did, however, identify a link between bowel disorders and regression in children with autism.
In their review of case notes, the team noted some parents provided a different history of their children after media reports about MMR.