The San Francisco Chronicle
There's No Vaccine Against Irrational Fears
by Howard Fienberg
OF ALL THE TRAGEDIES that can befall a parent, having an autistic child is one of the most frustrating. If something causes this developmental disorder, we need to know. Many parents believe that vaccination against other childhood diseases inadvertently causes autism. They see autism develop in children soon after the mandatory vaccinations against measles, mumps and rubella and see a dramatic increase in general autism incidence.
However, scientific evidence hints at no link between the MMR vaccinations and autism. Last month, the Institute of Medicine warned that we are risking serious outbreaks of disease due to insufficient vaccinations in adults and children. So it appears that the misguided battle against childhood vaccinations will only increase this risk without saving any children from autism.
Are rates of autism increasing? There have only been two large population-based studies in the United States, both in the 1980s, finding rates of 3.3 and 1.2 per 10,000 children. But the U.S. Department of Education shows that the number of children provided with special education service for autism rose by 556 percent from 1991 to 1997. So it is possible, but the data are confounded by a broadening of case definition as well as improvements in diagnosis. Autism is less likely to be misdiagnosed or ignored, and more mild cases are now being considered autism than in the past. According to Dr. Tina Iyama, associate professor of pediatrics at the University of Wisconsin at Madison, "Children (diagnosed as autistic) can be anywhere from severely or profoundly retarded to extremely bright but socially awkward.
More importantly, a study in the British medical journal Lancet by Brent Taylor, a professor at the University College Medical School in London, and colleagues in 1999 indicated that the United Kingdom's rise in incidence began in 1979, and the data showed no significant jump after the introduction of the MMR vaccine in 1998.
Many parents had long believed in the link, but the first widely accepted "evidence" only arrived in February 1998, with publication of a study in the Lancet by Andrew Wakefield of the Royal Free Hospital and School of Medicine in London. Wakefield and his co-authors concluded that the MMR vaccine might have caused a bowel disease, which might in turn have caused autism. But that was pure speculation, based on a collection of 12 patients. Four of those cases developed behavioral problems before any symptoms of bowel disease developed. In addition, the link between the measles virus and bowel disease, made by Wakefield and his colleagues back in 1994, has since been discredited. It would therefore be unwise to link the MMR vaccine to bowel disease, let alone autism, on the basis of this lone evidence.
The 1999 Taylor study dispelled many of the notions behind the Wakefield study. Besides the chronological link between the rise in autism and the introduction of the MMR vaccine, it found no relationship between the onset of autism and whether children were vaccinated before or after 18 months of age. Although the concern of parents usually arose about six months after vaccination, the Taylor study found initial diagnoses or signs of autism were no more likely to occur after vaccination than before.
What is beyond doubt, however, is that serious and deadly epidemics would result if we rejected the MMR vaccine. Measles is often considered the most threatening. Dr. Iyama says that "people forget what measles encephalitis is like." Life has improved. Measles cases overall dropped 98 percent upon the introduction of a measles vaccine in 1963. But a resurgent outbreak in 1989-1991 should serve as a stark reminder that these diseases are not mere "nuisances." It struck 55,622 people, mostly children under 5, resulting in more than 11,000 hospitalizations and 125 deaths. The Centers for Disease Control and Prevention blame low vaccination coverage.
What is the best way to deal with this problem? Congressional intervention might seem attractive, but it has so far been less than helpful. Rep. Dan Burton, chairman of the House Government Reform Committee, has held hearings to denounce the MMR vaccines, which he believes causes autism. But politicizing medicine like this usually just obscures more important issues.
Parents have always been vulnerable to health scares: power lines near their children's schools, alar coating their apples or air pollution asphyxiating their toddlers in their cribs.
Intentional or not, drumming up hysteria without reasonable supporting evidence unfairly plays on parental fears, blinding parents to the real risks they and their children face. While avoiding the MMR vaccine is unlikely to prevent autism, such action increases the risks of recurrence of epidemic diseases such as the measles or rubella.
Howard Fienberg is research analyst at the Washinton-based Statistical Assessment Service, a nonprofit, nonpartisan organization dedicated to improving public understanding of scientific and social research. Its Web site is www.stats.org.
(see the original article at http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2000/07/05/ED76651.DTL )
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