Many studies have been conducted on large samples to determine if a link exists between vaccination – specifically the measles-mumps-rubella (MMR) and thimerosal-containing vaccines – and increases in the prevalence of autism. These studies have not supported a link between either the MMR vaccine or thimerosal and the increased prevalence of autism. Scientific evidence indicates that the proven benefits of vaccinating a child to protect them against serious diseases outweigh the hypothesized risk that vaccinations might cause autism. It is possible that, in rare cases, an immunization might trigger the onset of autism symptoms due to an underlying medical or genetic condition. Autism Speaks is conducting studies on the underlying biology of autism, including studies to better understand medical and genetic conditions that are associated with autism.
Autism Speaks is funding research to develop effective treatments for individuals with autism spectrum disorders across the lifespan. We support a wide range of studies that are exploring behavioral, biomedical and pharmacological treatments. Parents need and deserve research to answer questions regarding what treatments are effective for their child.
On Monday, September 13, 2010, the journal Pediatrics published the results of a scientific investigation that explored whether mercury exposure, through the vaccine preservative thimerosal, resulted in an elevated risk of autism. Using a case-control design, this study found no association between thimerosal exposure and autism, autism spectrum disorder, or regressive autism.
This study is unique from previous reports because it interviewed parents and used direct observations of child behavior to identify subgroups of autism, including regressive autism. All individuals who were included in the study, including those without autism, were screened using a tool called the Social Communication Questionnaire; thus, children with mild adverse neurodevelopmental outcomes that were not diagnosed as autism were not included. In order to calculate thimerosal exposure, the investigators documented thimerosal exposure through child and maternal medical charts and medical records. The analysis conducted also controlled for a wide variety of preexisting medical co-morbidities and potential confounding factors that were discussed and agreed upon by an external advisory committee.
No significant increase in risk of autism or regressive autism was observed with elevating levels of thimerosal exposure during any of the four time periods analyzed, including the prenatal period. The results of this study add to a large body of literature showing that thimerosal is not associated with a higher risk for autism. Thimerosal has now been removed from childhood vaccinations due to public concern over the preservative. . Details about the study, including rationale for the adjusted analyses and confounding variables, and additional analyses can be found on the website of the independent agency contracted to conduct the study.
For more information, please read Autism Speaks statement on the vaccines and autism.