The Theories About Autism And Vaccines

Sharyl Attkisson is an investigative correspondent for CBS News.
Vaccines have saved countless lives, nearly eradicating horrible, deadly and disfiguring diseases that once threatened many Americans. Most government scientists and public health officials discount any link between these lifesaving medicines and autism or ADD. But what is it about vaccinations that some parents and scientists believe is possibly implicated in these disorders? There are many theories.

One vaccine researcher (who does not believe a link between vaccines and autism or ADD has been firmly established) told me that the theories are not mutually exclusive; that there could be some validity behind each.

Thimerosal (a mercury-based preservative): commonly used in many childhood vaccines through the 1990's, concern over parents who believed their children were getting autism and ADD from vaccines led the government to recommend voluntarily phasing it out of vaccinations, while at the same time maintaining there was nothing to worry about. It is still widely used in flu shots. However, parents, if they know to do so, can ask their doctor for mercury-free (thimerosal-free) flu shots if they choose to vaccinate their children against flu. While everyone knows mercury is a neurotoxin, many studies have attempted to look at the effects of mercury and/or this particular form of mercury and the findings are divided. The government and many scientists have maintained that children have a natural ability to expel mercury from their bodies. However, other scientists have suggested this ability to excrete mercury is impaired in some children, and they may become injured.

DPT: According to the government, the special federal vaccine court was started by Congress in 1988 in response to many reports of DPT side effects. According to CDC, "reports of harmful side effects following DTP (diphtheria, tetanus, pertussis) vaccine posed major liability concerns for vaccine companies and health care providers and caused many to question the safety of DTP vaccines... (vaccine makers) decided to leave the marketplace creating significant vaccine shortages and a real threat to the Nation's health." (

Vaccine court was created to shield vaccine makers from liability and keep the vaccine supply steady. In vaccine court, the government defends the vaccines, and the vaccine makers don't have to pay victims; victims are paid from a .75 tax you pay on each dose of vaccine you or your child gets. To date, there have been more injury and death claims filed for DTP than any other vaccine (11,430 injuries and 977 deaths). Because DTP was responsible for a higher than acceptable rate of brain injury, according to the CDC, the formulation was changed in the 1990's to DTaP because it is believed to be safer. Public health officials still maintain that getting this vaccine is much safer than not getting it. But because some of the brain damage reported after DTP resulted in autism or autism-like symptoms, some people believe there's a connection.

MMR: Many parents claim their child's regression into autism occurred right after the MMR (measles, mumps, rubella) vaccine. MMR contains live measles virus to work, so it never had the mercury preservative in it (mercury would kill the live virus). But because measles has been found in the intestines of some autistic children, and the only known exposure was the MMR shot; and because so many autistic children have gastrointestinal problems, some parents and researchers believe there may be a link. On the other hand, health officials point out that measles can be a devastating disease and, according to one, once was responsible for about 2,000 cases of brain problems a year (before it was controlled by vaccines).

Multiple Vaccinations: Many parents saw their children regress into autism immediately after a large battery of shots; as many as nine doses in one doctor's visit. Some believe that instead of having the appropriate immune response, certain children, for reasons that aren't clear, become very sick. This is one reason why doctors caution not to vaccinate your children while they are ill. Some parents and doctors believe it's safer to split up the shots on different days, including separating MMR into three shots on different days, and doing the same with DTaP. However, public health officials maintain there's no medical reason your child can't get unlimited shots in one visit.

To see the statistics of vaccine injury claims and compensation paid to date, click here.

(Note: CBS News has obtained documents showing a small number of cases that resulted in brain injury and autism or autism-like symptoms have been compensated in vaccine court, but that is not reflected in the chart which officially shows "no" autism claims compensated.)

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    Sharyl Attkisson is a CBS News investigative correspondent based in Washington.