University of Missouri - Columbia.
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Posted 09.23.05

MU Researcher Finds No Link Between Autism and Immunizations

Parents Should Immunize Children

COLUMBIA, MO -- Immunizations are a staple of early childhood; however, a controversy over whether there is a connection between vaccines and autism continues despite scientific evidence to the contrary. A University of Missouri-Columbia researcher is now adding her own evidence to the debate that points to the safety of immunizations.

At the center of the controversy is thimerosal, a mercury-containing preservative that was used in some vaccines to protect multi-dose vials from bacterial contamination. Scores of scientific studies have been conducted and the overwhelming majority has found no trace of a connection between the increase in autism and thimerosal. However, in spite of this finding, in the United States thimerosal was removed from all routine childhood vaccines between 1999 and 2001.

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"Many children with autism start to develop autistic symptoms around the same time as they receive immunizations," said Judith Miles, professor of pediatrics, Thompson Endowed Chair of Child Health and Pathology, and director of the Medical Genetics Division at MU. "Obviously, it is worrisome to families and it seems reasonable to conclude that a relationship exists. However, if you look at the data there is simply no relationship between them. There has been no thimerosal in Denmark's vaccines since 1991 and yet diagnosed cases of autism there rose at the same rate as it did worldwide."

Miles also is conducting research on the effects of exposure to thimerosal during pregnancy. The study involved women with a certain condition who must receive Rh immune globulin shots during pregnancy. Those women are exposed to thimerosal since it is an ingredient in the injections they receive. Therefore, Miles hypothesized if thimerosal is a risk factor for autism then this group of women should give birth to a greater number of autistic children.

"We conclude that there is no indication that pregnancies resulting in autistic children were more likely to be complicated by Rh immune globulin/thimerosal exposure," Miles said. "This data suggests there is no role for thimerosal in the development of autism."

Miles presented her study - "Rh Immune Globulin in Pregnancy: Relationship to Autism Development" - at this year's national meeting of the American College of Medical Genetics. The study included mothers of autistic children who were evaluated at the MU Autism Clinic from 1995 to 2005.

The Institute of Medicine and the National Academy of Sciences - both independent bodies - convened groups to examine all the studies and the evidence involved in this controversy. The most recent report concludes there is no connection between thimerosal and autism. The main concern, Miles said, is that parents will opt not to immunize their children because of this unfounded scare.

"There is no doubt that immunizations represent the safest, most effective means of protecting people from serious, often life-threatening diseases, that have ever been devised. The most important reason for this is that they provide a natural protection, one which mimics the protection provided by nature," said Ted Groshong, past president of the Missouri chapter of the American Academy of Pediatrics.



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