March 5, 2004 -- The researchers behind a controversial British study that proposed a possible link between the MMR (measles, mumps, rubella) vaccine and autism are now taking issue with their own study and rejecting the findings.
The formal retraction comes after a newspaper investigation revealed that the lead researcher in the study received funding from a legal aid group that was seeking legal action on behalf of parents who believed the MMR vaccine harmed their children, a conflict of interest not disclosed at the time of publication.
The release of the study in 1998 triggered a collapse in the U.K.'s child vaccination program and led to subsequent measles outbreaks after concerned parents withheld the MMR vaccine from their children.
In the U.S., the study was frequently cited by a small but vocal minority of parents opposed to the use of vaccines in children.
The retraction appears in the March 6 issue of The Lancet, which is the journal that originally published the 1998 study. The three-paragraph retraction was signed by 10 of the original 13 original researchers of the report.
"We wish to make it clear that in this paper no causal link was established between MMR vaccine and autism as the data were insufficient," write the researchers.
"However, the possibility of such a link was raised and consequent events have had major implications for public health. In view of this, we consider now is the appropriate time that we should together formally retract the interpretation placed upon these findings in the paper, according to precedent."
Conflict of Interest Casts Doubt on Findings
The lead researcher of the 1998 study, Andrew Wakefield, MD, did not sign the retraction and says he stands by the findings of the study.
In a statement published in The Lancet, Wakefield says the investigation he was conducting on behalf of the legal aid group was completely separate from the study that showed a link between MMR vaccination and the development of an autism-like developmental disorder in 12 children with an inflammatory bowel syndrome.
But the experts say the fact that Wakefield was conducting an investigation on possible grounds for legal action on behalf of the parents of some of the same children involved in the other study is a conflict of interest that should have been disclosed prior to publication.
"We regret that aspects of funding for parallel and related work and the existence of ongoing litigation that had been known during clinical evaluation of the children reported in 1998 Lancet paper were not disclosed to editors," writes Richard Horton, editor of The Lancet, in an editorial that accompanies the retraction.
Horton says that if the editorial board and editors had known then what they know now, it would have affected their decision to publish the study.
Retraction Likely to Close the Door on MMR Controversy
The 1998 study did not prove an association between MMR and autism, but concluded that, "further investigations are needed to examine this syndrome and its possible relation to this vaccine."
Since the Wakefield study was published, several major studies -- including a report from the U.S. Institute of Medicine -- have examined the issue and found no proof of a link between the MMR vaccine and autism.
"The positive side, if there is a positive side to that publication, is that it caused the public health community both here and in the U.K. to focus very closely on the issue of vaccine safety," says David Neumann, PhD, executive director of the National Partnership for Immunization.
"Since that publication in 1998, there have been any number of studies here and overseas that have looked at the relationship between vaccines and autism and autism spectrum disorders," Neumann tells WebMD, "and the epidemiological studies have consistently shown no linkage between vaccine use and the development of neurological changes."
Samuel Katz, MD, who helped develop the measles vaccine currently in use, says he'd be surprised if the retraction didn't shut the door on the MMR-autism controversy.
"I can't imagine that it doesn't totally exonerate MMR," says Katz, who is also professor of pediatric infectious diseases at Duke University.
Neumann agrees, but takes a more pragmatic approach.
"There is segment of population here in the U.S. that is skeptical about using vaccines, and the Wakefield articles and others of that type have reinforced their impressions," says Neumann. "Yet though that the paper has now been discounted, and the authors have retracted their findings, the public health community will constantly be challenged by those findings over the coming years by people who fail to understand the science or appreciate the issues with that report."
But Neumann says the bottom line is that autism is a serious disease and deserves further research to understand what it is and how to treat it. In light of recent events, he says, ''to continually invest in research trying to find an association between vaccine use and autism isn't probably a good use of those resources."