Ian Sample, science correspondent
The Guardian
Any remaining concern over a link between autism and MMR has been dispelled by a new study that found withdrawing the vaccine did nothing to slow the rise in children diagnosed with the condition.
Fears that the triple vaccine for measles, mumps and rubella could cause autism were first raised in 1998 by a gastroenterologist, Andrew Wakefield, but his research has been largely discredited.
Parental concern over the vaccine did cause a slump in its uptake, which has fallen to 60% in some parts of Britain, prompting health officials to draw up contingency plans to combat a possible measles epidemic.
Scientists have examined rates of autism among children in Japan, where the MMR vaccine was withdrawn in 1993. They found that the number of children with autism continued to rise after the MMR vaccine was replaced with single-shot vaccines.
During the study, the medical records of 31,426 children in the city of Yokohama were checked. Before the vaccine was withdrawn, between 48 and 86 children per 10,000 were diagnosed as autistic. After the vaccine was withdrawn, 97 to 161 children per 10,000 were diagnosed with the condition.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 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's lead scientist, Dr Hideo Honda of the Yokohama rehabilitation centre concludes in the Journal of Child Psychology and Psychiatry. The study, which is reported in today's New Scientist, was carried out with a team at the Institute of Psychiatry in London.
Despite the controversy that surrounded MMR after the publication of Dr Wakefield's research in the Lancet medical journal, no epidemiological study has found a link between 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, saying it added to a large body of evidence that showed there was 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 even-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."
Computer models used by the Health Protection Agency have suggested 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, said: "This is the only study where it has been possible to look at what the impact of withdrawing the vaccine is on the prevalence of 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 still trying to work out what 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.
The Guardian
Any remaining concern over a link between autism and MMR has been dispelled by a new study that found withdrawing the vaccine did nothing to slow the rise in children diagnosed with the condition.
Fears that the triple vaccine for measles, mumps and rubella could cause autism were first raised in 1998 by a gastroenterologist, Andrew Wakefield, but his research has been largely discredited.
Parental concern over the vaccine did cause a slump in its uptake, which has fallen to 60% in some parts of Britain, prompting health officials to draw up contingency plans to combat a possible measles epidemic.
Scientists have examined rates of autism among children in Japan, where the MMR vaccine was withdrawn in 1993. They found that the number of children with autism continued to rise after the MMR vaccine was replaced with single-shot vaccines.
During the study, the medical records of 31,426 children in the city of Yokohama were checked. 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 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's lead scientist, Dr Hideo Honda of the Yokohama rehabilitation centre concludes in the Journal of Child Psychology and Psychiatry. The study, which is reported in today's New Scientist, was carried out with a team at the Institute of Psychiatry in London.
Despite the controversy that surrounded MMR after the publication of Dr Wakefield's research in the Lancet medical journal, no epidemiological study has found a link between 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, saying it added to a large body of evidence that showed there was 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 even-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."
Computer models used by the Health Protection Agency have suggested 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, said: "This is the only study where it has been possible to look at what the impact of withdrawing the vaccine is on the prevalence of 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 still trying to work out what 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.
Clouons donc définitivement le cercueil de cette croyance sans fondement. Il n’y a pas de relation causale entre la vaccination ROR et l’augmentation des cas d’autisme. Les cas d’autisme ont continué d’augmenter malgré le retrait du vaccin au Japon en 1993. Il est intéressant de constater que le consensus scientifique n’a pas varié, seule une poignée ayant suspecté le vaccin ROR. Pourtant la presse s’est fait largement l’écho des théories de cette poignée d’individus, donnant l’impression d’une communauté scientifique divisée.
