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The MMR Vaccination-Autism Controversy

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Updated November 06, 2009

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

What Is the MMR?

Unlike the flu vaccine and a number of other childhood immunizations, the mumps/measles/rubella vaccine does not and did not contain thimerosal (a mercury-based preservative). MMR is one of several live viral vaccines (chicken pox vaccine and the nasal flu vaccine are two others). It is routinely given at 12 to 15 months of age, which is the age when autism is first likely to become evident.

How Did the MMR Vaccine Become So Controversial?

The concern over MMR began when Dr. Andrew Wakefield, a British gastroenterologist, tested 12 youngsters with and without autism and found a possible link between measles virus in the gut and autism. The theory presented was that certain children have a genetic predisposition to immune issues -- and that a variety of environmental toxins begin to attack the child's immune system early on.

Researcher's at Wakefield's Texas-based foundation called Thoughtful House, claim that "The child develops a leaky gut, tissue damage gets worse, the immune system grows weaker, and autoimmune reactions start. Then a lot of children experience a catastrophic event. Either in the form of a significant illness or a live virus vaccine. The immune system is overwhelmed and the child rapidly goes downhill. Some parents report a gradual deterioration, but many children seem to develop autism after a particular event. They go into the hospital or they get an MMR shot and they’re never the same again. Autism is the end result of this developing series of reactions." These claims have not been supported by any other studies including those that attempted unsuccessfully to replicate his results. More than 20 peer-reviewed epidemiologic studies have shown no link between MMR and autism. In fact, Dr. Wakefield’s original study was completely discredited. Ten of the 12 authors withdrew their support from the article.

The CDC's Perspective

Again, the CDC, the Institutes of Medicine, and other major research institutions looked into the issue, and found that there was an enormous amount of evidence that there is no connection between the MMR vaccine and autism and that there is no credible evidence that a link did exist. Some studies have suggested that autistic children do have more gastrointestinal problems. In addition, some research suggests that some kind of interaction between genetic predispositions and environmental issues may contribute to autism. As with the issue of thimerosal, there have been suggestions that research conducted by government agencies has been flawed or that evidence has been withheld from the public. Some MMR opponents claim that researchers who work for NIH and CDC come from and return to large pharmaceutical firms -- and they and their firms have a great deal of money at risk.

The bottom line:

Much is not known about the cause or causes of autism. A combination of environmental factors and genetic predisposition may indeed play a significant role in the causation of autism. The overwhelming weight of scientific evidence, however, tells us that vaccines like MMR or preservatives like thimerosal are not causing autism.

Resources:

Sources:

CDC Factsheet on MMR and Autism.
Thoughtful House FAQs.

Email Interview with Thoughtful House research staff.

Science Daily: "The Age of Autism:Pox Parts 1-4".

"Deadly Immunity" in Rolling Stone Magazine, June 20 2005. F. DeStefano Thimerosal-containing vaccines: evidence versus public apprehension. Expert Opin Drug Saf. 2009 Jan;8(1):1-4.

H Honda et al. No effect of MMR withdrawal on the incidence of autism: a total population study. J Child Psychol Psychiatry. 2005 Jun;46(6):572-9.

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