Vaccine-autism link unsupported by science, but theory lives on

At the Autism One conference in Chicago on Memorial Day weekend, hundreds of parents and clinicians gathered to hear a keynote by Jenny McCarthy, an actress and the mother of an autistic child, who has publicly associated her child's illness with vaccines. Many conference sessions were dedicated to doubts about immunizations. And, even when it wasn't the focus, the notion that some aspect of vaccines may play a role in autism was evident.

As the number of children diagnosed with autism has increased, so has the number of national support groups like this one. Parents often turn to these organizations for help in finding an explanation for their child's condition.

"Is the vaccine association real? Yes, I think it is. The future is going to see some major advances in our understanding of vaccine strategies that are safer for many, many more children," said Dr. Andrew Wakefield, who was among the conference's most well-known speakers. He also is the executive director of Thoughtful House Center for Children in Austin, Texas. He is not licensed to practice medicine in that state.

Dr. Wakefield was lead researcher for the controversial 1998 paper published in The Lancet, which linked the measles, mumps and rubella vaccine with gastrointestinal disease and developmental regression in 12 children.

His Autism One speech outlined his side of the story regarding some of the fallout from that paper -- specifically, the United Kingdom's General Medical Council hearings, which will continue through August. At these proceedings, the council is considering allegations of misconduct surrounding his research. The charges could result in the removal of his right to practice medicine in his home country. It also is reviewing the contributions of two co-authors on the 1998 paper. Dr. Wakefield denies the charges of any wrongdoing. His speech received a standing ovation.

Two different perspectives

Day in and day out, physicians spend time refuting the theory that vaccines play a role in the development of autism. The idea has been extremely tough to put to rest, even though significant scientific efforts, numerous studies and multiple evidence reviews have found no link.

"Scientific data overwhelmingly shows that there is no connection between vaccines and autism," said AMA Trustee Edward L. Langston, MD. "Autism is a heart-wrenching condition, and the upheaval felt by parents whose children have been diagnosed with autism is understandable -- as is their search for answers. We need more research to investigate the actual causes of autism."

But those on the other side of the issue say the studies dismissing the relationship are not conclusive. They wonder about the impartiality of the Centers for Disease Control and Prevention, which has carried out many of the investigations but promotes vaccine uptake as a part of its mission to improve public health.

In addition, people in this camp want biological rather than epidemiological studies and resent being labeled "anti-vaccine." They say they are seeking safe vaccines for all children, including the ones they suspect may have been harmed because of a genetic predisposition.

"I don't feel that vaccines cause or have caused autism, but I do believe that many of our children have problems with toxins, the metals that they may be exposed to, and the things we add to vaccines," said Nancy O'Hara, MD, a pediatrician from Wilton, Conn., who presented data on this subject at the Defeat Autism Now clinicians' seminar, which preceded the Autism One convention. "These children cannot detoxify as well as neurotypical children. ... We need a more individualized approach to giving vaccines, and to look at these genetically predisposed children in a different way."

Some also argue that, even though thimerosal has been removed from most vaccines, there's still enough to cause problems. And if thimerosal is not to blame -- because that's never been proven -- then something about vaccines is causing autism.

Every so often, a small study such as the one conducted by Dr. Wakefield comes along to buttress that belief. In this case, the momentum has held, even though 10 of the 13 authors on the 1998 paper published a statement in The Lancet in 2004 retracting the original interpretation that their data indicated a causal link between MMR and autism, and Dr. Wakefield faces significant professional scrutiny.

To many, such retractions and medical board inquests are part of a conspiracy. "It's a witch hunt," said Mayer Eisenstein, MD, JD, MPH, a lawyer and medical director of Homefirst Health Services in Chicago, who presented a session on vaccination at the Autism One meeting. "These combination vaccines cannot be right."

Rebuilding trust

This degree of staying power is why those who work on vaccine issues speak of the need not only to investigate possible adverse events but also to rebuild public trust surrounding the entire enterprise. A special article published in the July Pediatrics called for more public engagement in immunization issues and education on the complexity of the vaccine safety system. The article also urged that more time be allowed to build understanding about the rationale behind new vaccines before promoting them, and that reliance on mandates to force parental compliance be reduced.

"It's quite clear that the issues are really complex and don't lend themselves to sound bites," said Louis Z. Cooper, MD, lead author and professor emeritus in the Dept. of Pediatrics at Columbia University's College of Physicians and Surgeons in New York. He also is a former president of the American Academy of Pediatrics, although he was speaking personally.

The steps outlined in that article are needed because, experts say, despite all the science supporting vaccine safety, this confidence has not necessarily been conveyed to the public. A Web search on the word "vaccines" will turn up many sites that question such assertions. Moreover, the general public has a tendency to internalize the horrors of individual cases -- whether about a child down the block, the experience of a friend-of-a-friend-of-a-friend or a personal story found on the Internet -- rather than respond to population studies.

"It's very difficult to communicate good science to the public, and it's very easy to scare people. It's very hard to unscare them," said Paul A. Offit, MD, chief of infectious diseases at Children's Hospital of Philadelphia. He is also the co-inventor of one of the rotavirus vaccines.

There's no question that the seeming impossibility of putting this theory to rest has done damage. In June, the United Kingdom's Health Protection Agency declared measles endemic for the first time since 1994 and announced the first death from the disease since 2006. In May, the CDC announced that more measles cases have been detected in the U.S. this year than in any year since 2001.