New Court Ruling
Childhood Vaccines Do Not Cause Autism
The Institute of Medicine has weighed in — and now so has the US government: On Feb. 12, three federal judges — special masters of the US Claims Court — ruled that there was insufficient evidence to support the claim that the MMR (measles, mumps, rubella) vaccine causes autism.
But whether the decision will end the anti-vaccine advocacy among some parents of children with autism remains to be seen. Attorneys for the plaintiffs announced they would appeal the ruling. And later this spring, judges are expected to rule on claims involving three other families seeking to prove the mercury-based preservative in vaccines, thimerosal, caused autism in their children.
In all cases, the parents are seeking compensation from the National Vaccine Injury Compensation Program, a federal program enacted in 1986 to reduce lawsuits against physicians and manufacturers, while providing a reduced burden of proof for those claiming vaccine injuries.
THE FIRST TEST CASES
More than 5,000 claims pertaining to autism and other problems related to the vaccines are pending in the court. To deal with the high-volume of cases, the Office of Special Masters, beginning in 2002, conducted informal meetings with attorneys for the petitioners involving the autism claims and the US Department of Health and Human Services, the respondent in the cases. They decided to address the claims in two stages: to inquire into the general causation issue — whether the vaccines cause autism and similar disorders and under what circumstances — and second, to apply the evidence obtained to “test” cases.
The hearings for the first three “test cases” began in 2007, focusing on reports pertaining to the children of Theresa Cedillo and Michael Cedillo (Michelle), Rolf and Angel Hazelhurst (William Yates), and Kathryn and Joseph Snyder (Colten).
In the Cedillo case, the plaintiffs argued that Michelle had developed autism, gastrointestinal symptoms, and a seizure disorder after receiving the MMR vaccine.
THE CORE QUESTIONS
Max Wiznitzer, MD, an autism expert at Rainbow Babies and Children's Hospital in Cleveland and an associate professor pediatrics and neurology at Case Western Reserve University, served as an expert witness for the government in the first round of cases.
“The cases focused on several core questions,” he told Neurology Today in a telephone interview. “Can thimerosal-containing vaccines cause immune dysfunction? Did immune dysfunction allow the measles virus contained in the MMR vaccine to persist in the body, and did the vaccine-strain measles cause the children to develop gastrointestinal and CNS problems, including autism?”
The medical experts for the Cedillo family contended that vaccine-strain measles was detected in lab tests after she received the MMR vaccine, that it caused immune dysfunction, and that the immune dysfunction predisposed her to develop gastrointestinal, CNS, and other medical problems.
But several witnesses for the government questioned the validity of the lab tests for evidence of measles, the reliability of the lab that did the testing and had since closed, and the interpretations of the finding. And, in Michelle's case, they argued that there were signs of autism before she began her vaccination schedule.
Also at issue, Dr. Wiznitzer noted, was the toxicity of the mercury-based preservative in thimerosal. The medical experts for the plaintiffs argued that mercury in high doses — specifically, methylmercury — can be toxic to humans. But the government experts explained that methylmercury has a different mechanism from the form of mercury found in thimerosal — ethylmercury — and that there was not good evidence to conclude the small amounts [of ethylmercury] contained in infant vaccines can damage infant immune systems.
“They essentially said that different types of mercury have distinct toxological properties and mechanisms,” Dr. Wiznitzer said, “so it is inappropriate to generalize and compare one to the other.”
HOW TO ADVISE PARENTS
Now the challenge remains how to communicate the science behind this decision to the public, said autism expert and investigator Nancy Minshew, MD, professor of psychiatry and neurology at the University of Pittsburgh School of Medicine. And pediatric neurologists and other clinicians who treat and diagnose autism should expect to be bombarded with questions following the Feb. 12 rulings.
“Families may appreciate a summary of the special masters' training to prepare them to judge scientific evidence, a summary of what constitutes good science, a brief summary of the arguments made for causation, and the evidence that the judges saw as overwhelmingly refuting these arguments and why,” she wrote in an e-mail message to Neurology Today. “People want to know what caused the court to rule and think as it did in these cases so they can validate for themselves the decisions made.”
If asked about the decision by patients, Dr. Wiznitzer added that clinicians can say that the research to date clearly and reproducibly shows that vaccines do not cause autism, irrespective of the claimed mechanism.
“They should refer parents to reliable sources of information about vaccine safety and adverse events, such as the American Academy of Pediatrics, which has formed a task force on vaccine safety, the Children's Hospital of Philadelphia, and the Institute for Vaccine Safety.”