In March a federal vaccine court ruled that the preponderance of the evidence suggested 9-year-old Hannah Poling's autism was caused by her childhood vaccinations. Autism activists immediately hailed the decision as the first official admission that vaccines can cause autism. In fact, it isn't nearly so clean-cut.
Anti-vaccine activists usually claim the preservative thimerosal, which contains mercury, causes autism. Yet no epidemiological studies support this assertion; in fact, the rate of autism has continued to increase since thimerosal was removed from childhood vaccines in 2001.
Poling suffers from a mitochondrial disease; her parents argued that receiving five vaccinations for nine different diseases all at once triggered her autism. The court found this "plausible" but not proven. Nevertheless, the Polings' theory was enough for a favorable judgment.
A 2007 study in the Journal of the American Medical Association found that childhood vaccinations have reduced hospitalization rates of nine infectious diseases by 90 percent or more during the last century. One sad irony is that people with mitochondrial diseases are more vulnerable to infections, so they especially benefit from vaccination.
Some 5,000 autism cases are pending in the vaccine court.