Autism and MMR, no link found

Fears that the triple vaccine for measles, mumps and rubella could cause autism were first raised in 1998 by a gastroenterologist, Andrew Wakefield, his research has been largely discredited and any lingering doubt of a link between autism and MMR has been completely dispelled by a new study that found withdrawing the vaccine did nothing to slow the rise in children diagnosed with the condition.

British health officials have been forced to draw up contingency plans to deal with a possible measles epidemic as Parental concern over the vaccine caused a slump in its uptake, which has fallen to 60% in some parts of the country.

In Japan, where the MMR vaccine was withdrawn in 1993. Scientists have found that rates of autism among children, continued to rise after the triple vaccine was replaced with single-shot vaccines.

The study checked medical records of 31,426 children in Yokohama and found that before the vaccine was withdrawn, between 48 and 86 children per 10,000 were diagnosed as autistic. After the vaccine was withdrawn, 97 to 161 children per 10,000 were diagnosed with the condition.

The study's lead scientist, Dr Hideo Honda of the Yokohama rehabilitation centre concluded that the vaccine "cannot have caused autism in the many children with autism spectrum disorders in Japan who were born and grew up in the era when MMR was not available".

The study, reported in the current issue of the New Scientist, was conducted with a team at the Institute of Psychiatry in London.

the controversy that surrounded MMR after the publication of Dr Wakefield's research in the Lancet medical journal, had no epidemiological study to link MMR and autism. Japan withdrew its version of the vaccine after reports that the mumps component was causing meningitis. A new version is to be introduced shortly.

Scientists and health officials welcomed the new study yesterday, it adds to a large body of evidence that shows no link between autism and MMR.

"Parents should take this as further reassurance that this is an effective vaccine that does not cause autism," said Dr David Baxter of the Greater Manchester Health Protection Unit. "Reading about MMR, it's easy for parents to think that the community was ever divided over this issue, but you could count on the fingers of one hand the number of people who suspected a link between MMR and autism."

The Health Protection Agency fears that the poor uptake of MMR could make an outbreak of measles in London imminent, followed by countrywide incidence. The agency estimates that about 300,000 children of primary school age and below in London are now susceptible.

Professor Patrick Bolton, an autism expert at the Institute of Psychiatry who was not involved in the research, confirms the study is the only one where it has been possible to look the impact of withdrawing the vaccine and the link with autism.

"All the previous studies have been making the case that with the introduction of the vaccine, there's been an increase in autism, but if the vaccine is really the cause, you'd expect that on its withdrawal the rates should reduce. The fact that they've continued to rise is really further evidence that MMR isn't causing it."

Scientists are examining which factors are behind the rising cases of autism.

"We know some of it is genetic, but so far a particular environmental factor that is responsible for autism has not been identified," Prof Bolton said.