In 1998, Dr. Andrew Wakefield and twelve other authors published a startling study that suggested a link between the MMR vaccine, inflammatory bowel disease, and autism. They found the measles virus from a vaccine (not the wild measles virus found in the community) in the bowels of twelve children with both inflammatory bowel disease and autism. They postulated that the virus somehow triggered the inflammation in the children’s bowels, and that somehow led to autism.
The supposed link was widely publicized, and as a result, parents all over the world refused to vaccinate their children with the MMR vaccine. In some countries, such as Great Britain, the vaccine rate for MMR grew so low that small epidemics of measles occurred, with some deaths. Now, instead of a possible risk of autism, parents faced a real risk of disease and death from the resurgence of measles.
In our mind, this study should have been a call for more research to see if the association was real. With only twelve subjects in the study, it is hard to know if the results were just a fluke or a real finding. Many times in medicine, a small study suggests a finding that a larger study then proves is false. In general, one large study is better than several smaller studies. In this case, the authors used a small study to declare that the MMR vaccine was a cause of autism. Several authors of the original study have since retracted that interpretation, but many parents had already made the decision not to vaccinate.
Most other studies since 1998, including several very large population studies with hundreds or thousands of participants, have failed to find any link between the MMR vaccine and autism. The most recent study on the matter was published on September 4, 2008. It sought to exactly reproduce Dr. Wakefield’s original study and compared twenty-five children with autism and bowel problems to thirteen children with bowel problems alone. The measles virus was found in only two children, one in each group, suggesting that it was not at all linked to autism.
In our opinion, the preponderance of the evidence suggests that there is no link between the MMR vaccine and autism. In addition, there is good evidence that autism has a genetic component. Twin studies show that if one identical twin has autism, the other twin has around a 90 percent risk of also having autism. However, fraternal twins have only a 10 percent risk of both having autism. This clearly supports a genetic basis for autism, as opposed to one caused by vaccines. We regularly reassure our patients that there is no increased risk of autism with the MMR or any other vaccine. Despite our reassurances, many parents still request delaying the vaccine and/or splitting the vaccine into its separate components.