A Neverending Story

Despite mounting scientific evidence to the contrary, thousands of families still ardently believe that vaccines containing the mercury-based preservative thimerosal are the cause of their children's autism. A study published Wednesday in The New England Journal of Medicine concluding that there is no correlation between thimerosal and neuropsychological development in young children is unlikely to dissuade them. And two articles accompanying the new study, including one that sounds the alarm about a coming onslaught of civil lawsuits against vaccinemakers by autism families, will hardly defuse the emotionally charged issue. Together, the three journal pieces highlight the the tangle of scientific, medical and legal strands underlying one of our most enduring and complicated public-health controversies.

The new study examined the relationship between thimerosal exposure from vaccines given in the first seven months of life, and neuropsychological development between the ages of 7 and 10. A total of 1,047 children provided a range of thimerosal exposures—from 0 to nearly 200 micrograms, or the most any child would get if they took all of the thimerosal-containing vaccines at the prescribed time. Researchers found no significant effect on speech, verbal memory, fine motor coordination, attention, behavior or general intelligence. "We consider this a reassuring study," says lead author William Thompson, a scientist with the Centers for Disease Control and Prevention (CDC). "Most of the 42 outcomes we measured were not associated with thimerosal exposure and the links we did find were on the order of what you would expect by chance." (Over the last 10 years, thimerosal has been removed from all childhood vaccines, except for some influenza vaccines.)

Thompson's study is the third since 2004 to examine the link between thimerosal and neuropsychological development. Five additional studies have focused on a possible link between thimerosal and autism, and another 10 studies have tested the relationship between autism and the MMR (Measles, Mumps and Rubella) vaccine. The MMR vaccine does not contain thimerosal, but some families believe it plays a role in autism. All of these studies have reached similar conclusions, but none of them have been enough to stem the tide of litigation.

Families claiming illness or injury due to a vaccine are required to file their claims with the federal Vaccine Immunization Compensation Program (VICP), otherwise known as vaccine court, which was created in 1988. VICP cases are decided by one of three federally appointed special masters—attorneys who essentially act as judges. Compensation is awarded from a "vaccine trust fund," established with vaccine taxes derived from a patient fee of 75 cents per innoculation. The fund currently holds more than $2 billion. Since 2001, nearly 5,000 families have filed complaints with the VICP alleging that a vaccine caused their child's autism, but to date, the VICP has never ruled in favor of a family claiming an autism-vaccine link. Still, the load of autism cases has turned standard VICP procedures on their head. According to court documents obtained by NEWSWEEK, for example, autism plaintiffs are no longer required to file medical records with their claims, because the VICP clerk's office does not have the space to accommodate such massive amounts of paper records.

Approximately 300 of the autism cases have been rejected outright. Nearly 1,000 families have opted out of the VICP system—which is permitted if the case is unresolved after 240 days, or if the VICP rules against a claim—and taken their cases to civil court, where they are suing the vaccine manufacturers directly. None of those cases have been decided yet. "The autism-thimerosal suits are different than anything that's ever happened," says Paul Offit, chief of infectious disease at Children's Hospital in Philadelphia, whose essay on the decision to remove thimerosal from vaccines despite a lack of scientific evidence showing the potential for harm was published Wednesday in the NEJM. While the scientific evidence is unequivocal, he says, the sheer number of cases alleging a link between thimerosal and autism, combined with the organization and political support that plaintiffs have garnered, is forcing scientists and legal experts to take notice. "The decisions pending now could have an enormous impact on the future of vaccine litigation."

Since its inception, the VICP has reviewed approximately 7,000 non-autism-related claims, including nearly 4,000 cases alleging injury or death from the DTP (Diptheria-Pertussis-Tetanus) vaccine. (The court was originally created to handle DTP cases.) Nearly a third of those non-autism cases have won average settlements of $850,000. But to win in vaccine court, the scientific evidence has to be on your side. The merit of a given case is largely determined by a simple table—established by a scientific advisory panel—that lists which medical conditions can be attributed to which vaccines. That table currently lists more than a dozen vaccines with medically recognized potential side effects, including paralytic polio from the live-virus polio vaccine and encephalitis from the MMR vaccine. Autism is not listed as a potential adverse outcome for any of the vaccines on the table.