In early February a US court ruled that parents who believe their children developed autism as a result of vaccinations were not entitled to compensation.
More than 5500 claims have been filed for compensation from a fund set up to compensate those who suffer injury as a result of vaccination - The National Vaccine Injury Compensation Program. The ruling was given in a test case involving children with autism from three different families.
Many parents are convinced that their children developed autism as a direct result of childhood vaccinations such as the measles-mumps-rubella (MMR) vaccine. This vaccine caused great controversy after British doctor Andrew Wakefield published a paper linking it with bowel disease and autism.
Solid scientific data linking vaccines and the development of autism has so far not been forthcoming but studies have hinted at possible associations. The leading theories regarding how vaccines might trigger autism are:
1. MMR Vaccine - causes autism by damaging the intestinal lining, which allows the entrance of encephalopathic (brain damaging) proteins.
2. Thimerosal - an ethylmercury-containing preservative in some vaccines, is toxic to the central nervous system.
3. Simultaneous administration of multiple vaccines overwhelms or weakens the immune system.
However, according to an Associated Press report the court heard that "it was abundantly clear that petitioners' theories of causation were speculative and unpersuasive." The court also said "the weight of scientific research and authority" was "simply more persuasive on nearly every point in contention."
The ruling was welcomed by government officials with a statement on the U.S. Department of Health and Human Services web site stating:
"The medical and scientific communities have carefully and thoroughly reviewed the evidence concerning the vaccine-autism theory and have found no association between vaccines and autism."
"If parents have questions or concerns about childhood vaccines, they should talk with their child's health care provider.
"Hopefully, the determination by the special masters will help reassure parents that vaccines do not cause autism," the statement added.
The Office of Special Masters, part of the U.S. Court of Federal Claims, still has to rule on claims from other families, as well as families who specifically believe thimerosal to be the causative factor in their childrens' autism.
However, the outlook isn't positive in these cases either according to the AP which reported that a judge had said, "The petitioners have failed to demonstrate that thimerosal-containing vaccines can contribute to causing immune dysfunction."
The ruling is unlikely to reassure parents or settle the autism-vaccine debate however, especially in the light of a number of important recent studies pointing the finger of blame for autism squarely at environmental factors and away from a purely genetic cause.
In January researchers from the University of California's M.I.N.D. Institute published research which found that environmental factors that foetuses and infants are exposed to, such as pesticides, viruses and chemicals in toys and household products, were likely to blame for the rise in the number of autism cases and should be studied more closely.
They analyzed a variety of data sources and found that genetics, and a greater awareness of the symptoms of autism leading to better diagnosis, simply could not explain the rapid and substantial rise in the number of cases of the developmental disorder of the past few decades.
Last year researchers from The School of Public Health and Health Services at George Washington University found a specific link between thimerosal exposure and autism incidence when they analyzed data from a vaccine safety database kept by the US Centers for Disease Control and Prevention (CDC).
Lead researcher Assistent Professor Heather Young said: These findings are important because they demonstrate that children in a birth cohort with higher average mercury exposure than other birth cohorts had rates of neurodevelopmental disorders that were on average 2 to 4 times higher than the rates in the birth cohorts with lower exposures.
She continued, Because of the strong ecological associations found in this study, it is extremely important that additional studies be conducted using this data source, including case-control and cohort studies which, would allow the linking of individual exposure to disease.
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