Autism and the MMR Vaccine; the National Institute of Child Health and Human Development (NICHD). (Medical Research Update)

Article excerpt

Some parents and families of children with autism believe that the Measles/ Mumps/Rubella (MMR) vaccine caused their children's autism. These parents report that their children were "normal" until they received the MMR vaccine. Then, after getting the vaccine, their children started showing symptoms of autism. Because the symptoms of autism begin to occur around the same time as the child's MMR vaccination, parents and families see the vaccine as the cause of the autism. However, just because the events happen around the same time does not mean that one caused the other. Although children receive many other vaccines in addition to the MMR vaccine, these other vaccines have not been identified as possible causes of autism.

These parents' beliefs and observations were reinforced by a small study of bowel disease and autism, published by Wakefield and his colleagues in 1998. The study's authors suggested that there was a link between the MMR vaccine and autism. This study did not include scientific testing to find out if there was a link. The authors relied on the reports of parents and families of 12 children with autism to make their suggestion. The study did not provide scientific proof that there was any link. Since this study was published in 1998, a number of other studies have also been published that suggested a link between the MMR vaccine and autism, but none of these provide scientific proof of such a link. To date there is no definite, scientific proof that any vaccine or combination of vaccines can cause autism.

Why do many doctors and scientists believe that the MMR vaccine does not cause autism?

In 2000 the Institute of Medicine (IOM) at the National Academy of Sciences, at the request of the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH), conducted a review of all the evidence related to the MMR vaccine and autism. This independent panel examined completed studies, on-going studies, published medical and scientific papers, and expert testimony to assess whether or not there was a link between autism and the MMR vaccine. The IOM concluded that the evidence reviewed did not support an association between autism and the MMR vaccine. This and other conclusions from the IOM review were released in April 2001 (Immunization Safety Review Committee 2001).

Also in 2000, the American Academy of Pediatrics (AAP), a professional organization for pediatricians, held a conference on the MMR vaccine and autism. Parents, scientists, and practitioners presented information on this topic to a multidisciplinary panel of experts. Based on its review, the AAP also found that the available evidence did not support the theory that the MMR vaccine caused autism or related disorders. The AAP policy statement appeared in the May 2001 issue of Pediatrics.

In 1999, Taylor and colleagues published a study that argued against the suggested link between autism and the MMR vaccine suggested in the Wakefield study. Taylor's study looked at all the known cases of autism spectrum disorder (ASD) in children living in certain districts of London who were born in 1979 or later. Researchers then matched the ASD patients with an independent registry of vaccinations. The results of this study showed that:

* The number of ASD cases had increased steadily since 1979, but there was no sharp increase in the number of cases after doctors started using the MMR vaccine in 1988.

* Children showed symptoms of ASD and were diagnosed with ASD at the same ages, regardless of whether they were vaccinated before or after 18 months of age. This finding is important because if the MMR vaccine caused ASD, the children who were vaccinated earlier would show symptoms earlier.

* By age two, vaccination coverage (the number of children who received vaccines) among children with ASD was nearly the same throughout the region as vaccination coverage for children the same age who did not have ASD. …