A special court ruled Friday that there is insufficient evidence to demonstrate that vaccines caused autism in three cases.

The cases, brought by the children’s parents, all alleged that vaccines containing thimerosol, a mercury preservative, caused or contributed to autism spectrum disorders in the children.

Thousands of parents of children with autism have filed petitions seeking compensation from the Department of Health and Human Services’ Vaccine Injury Compensation Program, a federal program intended to compensate victims of injuries caused by vaccines, since 2001.

A panel of “special masters” began hearing three other test cases in 2007 brought by parents of children with autism who also said vaccines caused the disorder in their children. In February 2009, a special court ruled that no link between autism and certain early childhood vaccines could be proven based on evidence presented in those cases.

But in the separate prominent case of Hannah Poling, a child with autism, the Vaccine Injury Compensation Program concluded in November 2007 that vaccinations she received as a toddler had “significantly aggravated” her underlying illness that had predisposed her to symptoms of autism.

Poling’s parents said in 2008 that their assertion that her illness was caused by childhood vaccines was vindicated by the federal government’s decision to compensate them.

(Source: http://www.cnn.com/)