Autism-vaccine link disproved again

There is no increased risk of autism spectrum disorder for infants exposed to ethylmercury from vaccines and immunoglobulin preparations containing the preservative thimerosal, according to a new study.

Researchers analyzed medical data on 1,008 children from three managed care organizations (256 with ASD and 752 without the disorder). They looked at prenatal and infant exposure to thimerosal.

"The study results indicated that exposure to thimerosal-containing vaccines, including during pregnancy, is not associated with developing ASD or specific ASD subtypes," said Frank DeStefano, MD, MPH, one of the study's authors and director of the Immunization Safety Office at the Centers for Disease Control and Prevention.

The study in the October issue of Pediatrics is the latest to disprove the autism-thimerosal link (link).

A 1998 study in The Lancet sparked fears of a link between autism and the vaccine for measles, mumps and rubella. The journal retracted the article last February, days after the General Medical Council, which licenses and disciplines British doctors, charged study investigator Dr. Andrew Wakefield with acting unethically for his disregard of the "distress and pain" of unnecessary tests on child subjects.

Even so, many parents still fear the preservative contributes to autism. A study published online March 1 in Pediatrics found that about one in four parents believes vaccines cause autism, and 11.5% have refused at least one recommended vaccination for their child.

The National Autism Assn., which maintains that vaccines cause autism in some children, was reviewing the new study, a spokeswoman said at this article's deadline.

In a Sept. 15 statement regarding a settlement in an autism-thimerosal court case, NAA Executive Director Rita Shreffler said thousands of children have been adversely affected by vaccines.

"Parents who observe regression and failing health following vaccines are told it's just coincidence. Many of us no longer buy that," she said. "We know that our children suffered brain injury from vaccines, resulting in a diagnosis of autism."

Dr. DeStefano said he hopes the new study will help allay the concerns of parents and pregnant women.

During the last decade, thimerosal has been removed or reduced to trace amounts in vaccines routinely recommended for children in the U.S., with the exception of influenza vaccine. But parents can request doses of thimerosal-free influenza vaccine, said Dr. DeStefano, who has done research in the area for nine years.

"The results of our study indicate that concerns about a possible increased risk of autism from thimerosal-containing influenza vaccines are unfounded," he said.