A special US court Friday ruled against the parents of an autistic child, rejecting their claim of a connection between autism and a triple vaccine for measles, mumps and rubella (MMR) their son was given.
In a similar ruling a year ago against three other families, the United States Court of Federal Claims said the "theory of vaccine-related causation (of autism) is scientifically unsupportable."
Like some 5,000 other families seeking compensation, the parents of William Mead, 11, argued that the MMR vaccine their son was administered in his first year triggered the symptoms of autism six months later.
They asked the special court to acknowledge that thimerosal, a mercury-based preserving agent in some vaccines like MMR, is the cause of autism in William.
"Petitioners have not shown either that certain children are genetically hypersusceptible to mercury or that certain children are predisposed to have difficulty excreting mercury," the court said in its 200-page ruling.
The "petitioners have not shown that the inorganic mercury deposited in the brain -- in the amount that could be received from a full complement of thimerosal-containing vaccines -- can cause the effects that petitioners have alleged," it added.
Several medical studies have given contradictory results on the alleged link between vaccines and autism. The latest, a Columbia University study published in September 2008, ruled out any relation between the two.
Last month, the prestigious British medical journal The Lancet retracted a 1998 study linking autism with MMR inoculation.
Doctors say the vaccine scare has resulted in a drop in child inoculation and a subsequent rise in measles, placing unprotected young lives at risk.