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MMR Vaccine Suit to Go Ahead in the US
March 9, 2001

By Mindy Hung

New York - Despite results of two new studies concluding that the measles-mumps-rubella (MMR) vaccine is not associated with a rise in the diagnosis of autism, parents' groups in the United States continue in their push to launch a class-action suit against the vaccine's manufacturers.

The studies, published in the February 24 issue of the British Medical Journal and the March 7 issue of The Journal of the American Medical Association, are only the latest chapters in a dispute between the medical community, which stands behind the inoculation, and a small but vocal group of parents and researchers who contend that the vaccine, when administered at too young an age, triggers an autoimmune reaction that leads to development of autism. Immunizations usually begin at 15 months, and diagnosis of autism often occurs soon after at 2-5 years.

Legal action against such industry giants as Pasteur-Merieux, SmithKline Beecham, and Merck is already taking place in the United Kingdom.

James Kaye, MD, MPH, lead investigator for the BMJ paper, told Medscape that the research was conducted with the intention of addressing the debate. "We were aware of the controversy...and we had available an excellent data source (the General Practice Research Database [GPRD]) which could be used to study the question."

Kaye and colleagues' analysis of the GPRD, a database that currently holds records on 3 million patients from general practices throughout the United Kingdom, revealed that the number of children receiving the triple inoculation held high and steady, with coverage at over 95% in successive birth cohorts. Rates of autism diagnosis, however, increased nearly 4-fold over time among 2- to 5-year-old boys born in 1988-1993.

The investigators write, "If the MMR vaccine were a major cause of the increasing incidence of autism, then the risk of autism in successive birth cohorts would be expected to stop rising within a few years of the vaccine being in full use."

Since the numbers of children found to have autism continued to increase regardless of how many received immunizations, Kaye and colleagues conclude that there is little evidence to indicate an association between vaccine and diagnosis. They speculate that the marked growth in reported incidence may come as a result of changes in diagnostic criteria, increased awareness of the condition among parents and general practitioners, or environmental factors not yet identified.

The JAMA study, conducted by Loring Dales, MD, of the immunization branch of the California Department of Health Services in Berkeley, posted similar results in children surveyed from 1980 through 1994.

The investigations also attempted to answer criticisms raised by Andrew Wakefield, FRCS, a researcher at Royal Free Hospital, University College London, whose studies, published in The Lancet in 1998, were the first to link the disorder with the timing of the vaccine. In a later editorial comment in The Lancet, Wakefield questioned the results of a smaller-scale time-trend analysis by Taylor and colleagues, published in The Lancet in 1999, contending that the sample was too modest.

Wakefield has continued to be vocal on the subject, writing a highly publicized editorial in the December issue of the Journal of Adverse Drug and Toxicological Reviews that alleged that early studies of MMR vaccine indicated safety problems and that the licensure was premature.

The United Kingdom, where the controversy has played out more prominently thanks, in part, to the lawsuit, has seen MMR immunizations drop to 88% overall, and down to 75% in some areas. The results of the latest BMJ and JAMA studies serve as vindication for government organizations, such as the US Centers for Disease Control and Prevention and Britain's National Health Service, which have long held that the vaccine is safe.

Government health officials, however, are still reminding the public that the success of vaccinations depends on higher coverage -- about 95% of the population needs to be inoculated in order to forestall spread of the diseases. The officials caution that preventing children from receiving inoculation constitutes a dangerous and needless threat to public health. The last measles outbreak in the United Kingdom, in 1980, killed 17 people.

Despite these warnings, it is likely that controversy will continue to surround the MMR vaccine. An article in the March issue of Archives of Disease in Childhood cites a connection between the triple inoculation and idiopathic thrombocytopenic purpura. Moreover, plans to launch a class-action suit in the United States against vaccine manufacturers are still under way, according to Ray Gallup, whose son Eric is autistic, a condition which Gallup attributes to a reaction to the MMR vaccine. Gallup has collected the names of more than 400 US parents who can relate similar experiences.

Gallup, who is also president and founder of the New Jersey-based Autism Autoimmunity Project, which funds research on the subject, noted that he would like to see immune tests performed on children before they receive vaccinations.

Immunization against measles, mumps, and rubella can also be administered individually at annual intervals; however, because no studies exist on the efficacy or timing of monovalent vaccines compared with the triple inoculation, it should not be considered a safer alternative to the MMR vaccine.

BMJ 2001;322(7284):460-463

Mindy Hung is an associate editor at Medscape.

MedscapeWire is edited by Deborah Flapan, an associate editor at Medscape. Send press releases and comments to medscapewire2@mail.medscape.com.