The U.S. government has concluded that childhood vaccines contributed to symptoms of autism in 9-year-old Hannah Poling. The unprecedented concession was in response to one of three test cases that allege the mercury-containing vaccine preservative thimerosal caused autism in children.

According to the case, the child was healthy and developing normally until her 18-month well-baby visit, where she received vaccinations for nine diseases, two of which contained thimerosal. Within 48 hours of the shots, Hannah become ill, refused to walk and could not sleep through the night. Within three months, she began showing signs of autism.

According to U.S. Division of Vaccine Injury Compensation, the shots "significantly aggravated an underlying mitochondrial disorder" and resulted in a brain disorder "with features of autism spectrum disorder."

Although federal officials continue to say there is no link between autism and vaccines, this concession says otherwise.

The U.S. Department of Health and Human Services has determined that Hannah’s family is entitled to compensation from a federal vaccine injury fund in an amount that is still being determined.

There are currently 4,900 autism cases pending in Federal "Vaccine Court."