Articles Title

National Institute of Child Health & Human Development
Autism and the MMR Vaccine

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 with over 55,000 members, 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 issue of Pediatrics (Halsey et al 2001).

In 1999, Taylor and colleagues published a study (Taylor et al 1999) 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 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 as vaccination coverage for children the same age who did not have ASD throughout the region. If the MMR vaccine and ASD autism were linked, then a greater number of children who had been vaccinated throughout the region would have ASD.
  • The first signs of autistic behavior or first diagnosis of ASD was not more likely to occur in time periods following the MMR vaccine than in other time periods.

Also in 1999, the United Kingdom’s Committee on Safety of Medicine examined hundreds of reports collected by lawyers of patients with autism and similar disorders that families said they developed after receiving the MMR or MR vaccine. After a systematic, standardized review of the case information, the Committee found that the information did not support any link between vaccines and autism. Based on the evidence, the Committee concluded that there was no cause for concern about the safety of MMR or MR vaccines (Medicines Commission Agency 1999).

A study, done in Sweden in 1998, also showed no evidence of association between the MMR vaccine and autism. The study compared the number of autism cases in children from two Swedish towns before 1982, when local doctors first started using the MMR vaccine, and after 1982. The results showed no difference in the rate of autism between the two groups of children in either town (Gillberg & Heijbel 1998).

Another study, done in England in 1997, looked at any possible link between the measles-specific vaccine (one part of the MMR vaccine) and different problems that result from damage to the nervous system, such as learning disabilities and behavior problems. These researchers found no proof that the measles vaccine was in any way linked to long-term damage to the nervous system (Miller et al 1997).

Last Update: 08/15/2006

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