Vaccine, Surge in Autism Unrelated, Study Says
The controversial idea that the dramatic upsurge in autism over the last two decades was caused by the measles-mumps-rubella vaccine--a concept embraced by many parents--is wrong, according to a new report released today by the California Department of Health Services.
The new study, like two others recently conducted in England and Finland, found that the rate of autism has been rising dramatically as the number of children vaccinated has remained virtually constant. This is convincing evidence, the researchers say, that the vaccine plays little or no role in the disease.
“We cannot rule out the possibility that in certain isolated, rare instances, the vaccine might have caused a rare case of autism,” said Dr. Hershel Jick of Boston University Medical Center. “But it is certainly not the major villain.”
Advocates of the autism-vaccine link dismiss the new reports, however, claiming bias on the part of their authors.
“I don’t know why anyone would believe information that comes out of a branch whose sole purpose is to promote immunization in California,” said Rick Rollens, a parent advocate who was instrumental in creating the MIND Institute for researching autism at UC Davis.
The studies in England and Finland are equally questionable, he added, because vaccine makers funded them.
And Dr. Bernard Rimland of the Autism Research Institute in San Diego argues that it is not the vaccine--known as MMR--alone that triggers autism, but the entire burden placed on the immune system by the 22 separate vaccines that are now given to children between birth and age 2.
“By focusing on MMR, these guys are missing the boat,” he said. “It’s much too early to dismiss the [vaccine] hypothesis.”
Despite those qualms, the new findings seemingly put researchers back to square one in trying to unravel the causes for the astonishing surge in a once-rare disorder, which has increased more than 500% in the last decade alone.
Autism is a severe developmental disorder in which children seem isolated from the world around them. There is a broad spectrum of symptoms, but the condition is marked by poor language skills and an inability to handle social relations.
In the 1970s, studies showed the incidence of autism to be about one case in every 2,500 children. Today, various studies, though controversial, suggest that the incidence is one in every 250 children, and perhaps even higher.
Though most researchers are convinced that genetic susceptibility lies at the heart of the disorder, it has become clear that some triggering agent in the environment plays an equally important role, either during gestation or soon after birth.
Researchers are investigating toxic chemicals, viruses, drugs, dietary changes and a host of other potential factors.
The purported link to MMR was first proposed by parents of autistic children, like Rollens, who observed that their children were apparently developing normally until they received the vaccine, at which point their development stopped or regressed.
Their suspicions were fanned by a 1998 report by Dr. Andrew Wakefield of the Royal Free Hospital in London, who identified 12 children who had undergone such regression within 14 days of being given MMR. The children also had gastrointestinal problems similar to irritable bowel syndrome, and Wakefield said he had identified the weakened virus used in the measles vaccine in their intestines.
Wakefield has argued forcefully that the viral infection may have allowed some potentially toxic components of food to leach into the bloodstream and travel to the brain, where they damaged neurons and produced developmental problems. He will soon publish a larger study of 170 such children showing the same results.
His findings have produced a furor in England, where many parents have demanded that the three components of the MMR vaccine be given separately at different times. A group of parents has also sued the vaccine’s manufacturer.
The new study, reported in today’s Journal of the American Medical Assn., rebuts such claims. It relies on extensive record keeping by the California health department.
The number of autism cases each year was determined by admissions to the state’s 21 regional centers for developmental disabilities, which provide special educational services to such children.
Vaccination data were obtained from yearly surveys of a random sample of kindergarten admissions, which yields birth dates and the dates of the immunizations required for school admission.
Dr. Loring Dales and his colleagues at the health department’s Immunization Branch in Berkeley found that the proportion of children vaccinated with MMR before the age of 2 increased only 14% from 1980 to 1994, while the number of children diagnosed yearly with autism increased 572%.
If MMR is the primary cause of the disorder, he said, the incidence should have jumped dramatically after the vaccine was introduced in 1971, then leveled off when the proportion of children vaccinated became constant. That did not happen.
Jick and his colleagues performed a similar study in Britain, and their results were published in the Feb. 17 British Medical Journal. Their findings were virtually identical to Dales’.
More than 95% of children in Britain receive MMR, Jick said. “Each year, the same number of children are being vaccinated, but there are more new cases of autism. The two really are disconnected.”
A Finnish study showed similar results.
Although Jick and other researchers are sympathetic to parents who are searching for the cause of their children’s disorder, they believe that the purported link arises only by coincidence. Autism is often first detected between the ages of 15 and 18 months, the same age at which MMR vaccination occurs.
“Given that virtually everyone is being vaccinated,” Jick said, “you will get a lot of instances where there seems to be time relationship. It would be surprising if there weren’t.”
Further negative evidence will be published in next month’s Archives of Pediatrics and Adolescent Medicine by Dr. Robert L. Davis of the University of Washington in Seattle. Davis focused on inflammatory bowel disease, which Wakefield says is triggered by MMR and proceeds to autism.
“We did not find any association in the long term between MMR and inflammatory bowel disease, nor any evidence that the vaccine triggered the acute onset of symptoms,” Davis said.
But advocates of the autism-vaccine theory are unimpressed. Most think that the disorder is an autoimmune disease caused by an overreaction to MMR and other vaccines in vulnerable children. During the same period in which autism rates have been rising, Rimland said, there have been startling increases in the rates of other autoimmune diseases, including asthma, allergies and diabetes.
“The idea is that there is an immune system dysfunction imposed by administering too many vaccines too close together,” Rimland said. In 1980, children received only eight vaccines by the age of 2, compared with the 22 given today. “There is good reason to believe that the immune system is not up to this kind of mistreatment,” he added.
Mercury added to vaccines as a preservative has also been proposed as contributing to the onset of autism because it produces many neurological symptoms that are the hallmark of the disorder. Although the amount in any one dose of a vaccine is small, studies show that children receiving several vaccines in one day could receive up to 1,000% of the maximum safe mercury intake.
Mercury was never used in MMR, but was present in some other vaccines, such as that for hepatitis B. Such vaccines have now been withdrawn from the market.
“It’s unfortunate, but parents are now fearing the vaccines more than the diseases they prevent,” said Dr. Jay M. Lieberman of Long Beach Memorial Medical Center. “They don’t remember what measles is”--and that it kills many of its victims, he said.
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No Link Found
Two new studies, one in California and one in England, indicate that the measles-mumps-rubella vaccine does not cause autism. The studies found that the incidence of autism has surged while the proportion of children vaccinated with MMR has remained relatively constant. Here are the results of the California study:
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Source: Journal of the American Medical Assn.
