Extensive review finds no relationship between vaccines and autism

The review was published online in the the journal Clinical Infectious Diseases. It looked at the three main hypotheses and shows how biological and epidemiological studies refute these.

The controversy began with a 1998 study in The Lancet that suggested a link between the combination measles-mumps-rubella (MMR) vaccine and autism. Dr. Offit and coauthor Jeffrey Gerber, MD, also of the Children's Hospital of Philadelphia, reviewed more than a dozen large studies, conducted in five different countries, that used different methods to address the issue, and concluded that no data supported the association between the MMR vaccine and autism. They concluded that the correlation between MMR vaccine and autism was a coincidence, because MMR is given at the age at which autism is usually diagnosed.

Also hypothesised as a cause has been the ethylmercury-containing preservative thimerosal, which was used in vaccines for over 50 years. However, the authors' review of seven studies from five countries showed that the presence or absence of thimerosal in vaccines did not affect autism rates.

The third suggestion has been that the simultaneous administration of multiple vaccines overwhelms or weakens the immune system. The authors explain that children's immune systems routinely handle much more than the relatively small amount of material contained in vaccines. Modern vaccines also contain far fewer immune-triggering components than did those of decades ago.

Worried parents have been chosing not to vaccinate their children, leading to a rise in vaccine preventable diseases.