No Links Found Between Childhood Vaccine, Autism

The controversial theory that the measles-mumps-rubella vaccine is largely responsible for the sharp increase in the incidence of autism over the last 15 years has no scientific justification, according to a report released Monday by the Institute of Medicine.

The report is the latest in a series of studies that have reached the same conclusion.

Epidemiological studies so far are too imprecise to rule out the possibility that a small number of children might be affected by vaccines, said Dr. Steven Goodman of the Johns Hopkins University School of Medicine, a member of the panel that wrote the report. But vaccines are unlikely to cause many cases, if any, and “the risk of not immunizing is much greater than any risk from immunizing,” he said.

“The simplest thing to tell parents is that [the link between the vaccine and autism] is not a relationship that has been proven,” Goodman added. “It’s the sort of theoretical risk that we can’t close the door on,” but current vaccination policies should be continued, he said.

Advocates of the vaccine theory were not entirely satisfied with the conclusions of the report, but were pleased that it had been undertaken in the first place.

“This is a vindication for those of us who have been trying to get mainstream medicine to take a look at this issue,” said parent advocate Rick Rollens, who was instrumental in creating the MIND Institute for researching autism at UC Davis.

As for the conclusions of the report, he said, “The jury is still out. . . . We’re pleased to see the recommendation for more good, independent research.”

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, the incidence of autism was about one in every 2,500 children. Today, various studies, though controversial, suggest the incidence is at least one in every 250 children.

The purported link to the vaccine was first proposed by parents of autistic children, like Rollens, who observed that their apparently normal children stopped developing or regressed shortly after receiving the vaccine.

Subsequently, Dr. Andrew Wakefield of the Royal Free Hospital in London identified 170 children who had undergone regression after receiving the vaccine and who had gastrointestinal problems linked to the weakened measles virus used in the vaccine.

In recent months, the World Health Organization and the British government have issued reports suggesting no link between vaccinations and autism. The American Academy of Pediatrics will release a similar report next week in the journal Pediatrics.

Supporters of the vaccination theory have charged that previous studies of the subject were conducted by researchers with strong links to the vaccine manufacturers, thereby rendering the studies suspect.

The new study, commissioned last fall by the National Institutes of Health and the Centers for Disease Control and Prevention, was produced by a group of highly respected researchers who had never worked for vaccine companies, never received funding from them and have not been involved in any vaccination programs.

The study was released early so that it would be available for congressional hearings on autism incidence scheduled for Wednesday.

The committee concluded that “the evidence favors rejection of a causal relationship . . . between MMR vaccine and [autism].” The primary reasons for that conclusion are:

* All the epidemiological evidence shows no link.

* Wakefield’s studies “are uninformative with respect to causality”--that is, he showed no evidence that the vaccine produced the problems he identified.

* There is no sound biological mechanism that has been shown in the laboratory by which the link could occur.

* There is no animal model that shows similar effects from the vaccine.

The panel’s head, Dr. Marie C. McCormick of the Harvard School of Public Health, noted that the government has a “major responsibility to ensure that MMR vaccine” is safe because children are required to receive it.

“The level of concern among parents about MMR safety is tremendous and must be addressed meaningfully,” she said.

“What this really tells us,” said Dr. Bruce Gellin of the Vanderbilt University School of Medicine, “is that we don’t understand the cause or causes of autism, and that is something that desperately needs more attention because of the impact on patients and their families.”

The report and an audio version of Monday’s briefing are available on the Web at https://www.iom.edu/ImSafety.