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

A central figure in advancing the concept may have his United Kingdom medical license revoked.

By Victoria Stagg Elliott — Posted July 28, 2008

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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.

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Fearing the vaccine more than the disease

After publication in The Lancet of the 1998 paper that associated the combination measles, mumps and rubella vaccine -- MMR -- with the development of autism, and thesubsequent media coverage, immunization rates in England dropped and the number of measles and mumps cases went up. While the percentage of children beingvaccinated is rising again, measles is now considered endemic there.

Percent of 2-year-olds in England who received at least one dose of MMR, and the number of cases of measles and mumps reported:

Shots Measles cases Mumps cases
1995-96 92% 112 93
1996-97 92% 177 170
1997-98 91% 55 116
1998-99 88% 92 370
1999-00 88% 99 699
2000-01 87% 67 770
2001-02 84% 305 421
2002-03 82% 394 1,101
2003-04 80% 181 7,480
2004-05 81% 77 39,621
2005-06 84% 736 4,152
2006-07 85% 958 1,427

Note: The time period for vaccination rates runs for the fiscal year from April 1 to March 31. Cases are for the calendar year. The case numbers for 2007 are provisional.

Source: Health Protection Agency, United Kingdom

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Mitochondrial disorders' role

In response to concerns about the association between autism and mitochondrial disorders, several federal health agencies in June convened a workshop in Indianapolis to discuss the science on this subject.

"Is there a segment of kids with autism who have underlying mitochondrial disorders?" asked Walter J. Koroshetz, MD, deputy director of the National Institute of Neurological Disorders and Stroke, one of the agencies sponsoring this event. "It's worth investigating to find out."

The workshop followed the United Mitochondrial Disease Foundation's annual symposium and was in part a response to the case of 9-year-old Hannah Poling. A special vaccine court awarded damages last fall to the Polings when it concluded that a series of shots may have aggravated an underlying mitochondrial disorder, leading to autistic-like symptoms.

That case reignited public concern about a possible link between autism and vaccines. Most physicians attending the workshop said, though, that the preventives were crucial for children with mitochondrial disorders because infections can cause them to deteriorate rapidly.

"The feeling is that the risk-benefit ratio is in favor of vaccinating kids with mitochondrial disorders," said Dr. Koroshetz.

In addition, significant interest emerged regarding further investigation of the links between autism and problems with this genetic material responsible for producing cellular energy. Researchers would like to set up studies that could lead to ways to screen for this issue in autistic children, because detecting such links is currently difficult.

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External links

Vaccine safety, Centers for Disease Control and Prevention (link)

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