A STUDY of more than half a million children in Denmark has concluded that the triple vaccine that protects against measles, mumps and rubella (MMR) does not cause autism.
鈥淚n the scientific community it should put this debate to rest,鈥� says Kreesten Madsen, head of the team at the Danish Epidemiology Science Centre in Aarhus. It is the largest study to look specifically at the claimed link between MMR and autism, and is also based on more reliable data.
Madsen鈥檚 team looked at the records of all 537,303 children born in Denmark between 1991 and 1998. Denmark notes when children are vaccinated and also when any are diagnosed with autism. Previous studies have had to rely on the potentially flawed or biased recollections of parents and doctors.
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The team found no difference in the rate of autism between the 440,655 children who were vaccinated and the rest, who weren鈥檛 鈥� about 3 per 1000 children in both groups. Nor was there any association between the age at which children were diagnosed and the age when they were vaccinated (The New England Journal of Medicine, vol 347, p 1477).
鈥淚 hope we can convince parents who are undecided to have the vaccine, but there鈥檚 definitely a group we won鈥檛 be able to convince,鈥� says Madsen. That group includes SafeMinds, an anti-vaccination group based in New Jersey. Spokeswoman Sally Bernard says the vaccine has only been linked with 鈥渞egressive autism鈥�, a subclass of the disorder where children develop normally at first but suddenly deteriorate. By failing to analyse these cases separately, the Danish study fails to settle the issue, she says.
Bernard says regressive autism accounts for 10 to 20 per cent of cases. But Madsen says the proportion is even larger 鈥� about a third of all cases. 鈥淚f there was a significant increase in a subgroup that size, it would have showed up in our data,鈥� he says.