Science Panel Finds No Link Between Autism and MMR Vaccine
WebMD News Archive
April 23, 2001 (Washington) -- A panel of independent experts
has concluded that the measles, mumps, and rubella vaccine, or MMR, does not
cause autism, a devastating brain disorder for which there is no cure. But the
announcement by the 15-member committee convened by the National Academy of
Sciences' Institute of Medicine (IOM) left the door open just a crack, which
could allow the controversy surrounding the MMR vaccine to continue.
In its report released Monday, the IOM said that after
considering evidence available today, it is reasonable to conclude that the
vaccine does not cause autism. The scientists also said the evidence that does
exist "shows no association" between the vaccine and the condition.
Nonetheless, the panel could not rule out that MMR vaccine could contribute to
autism in a small number of children.
One highly publicized and disputed 1998 British study brought
suspicions about the vaccine to the forefront. It involved 12 children who had
received MMR shots. They seemed to develop normally at first, but then
developed bowel problems and regressed emotionally, exhibiting autism-like
symptoms, such as bizarre ritualistic or repetitive behaviors.
Both the CDC and the National Institutes of Health asked the
Immunization Review Safety Committee to evaluate the autism-MMR connection. The
IOM committee then reached its conclusion about MMR and autism, which is
similar to the conclusions made by the American Academy of Pediatrics and the
World Health Organization.
After reviewing the existing literature, the panel could find
no biological mechanism for the vaccine-disease relationship, nor could members
justify the theory that a viral infection like measles, triggered by the
vaccine, could produce bowel inflammation that may leak into a person's system
and produce a kind of brain poisoning.
MMR vaccine supporters, however, are convinced of the benefits
of the shot. They note that the three-in-one injection has virtually eliminated
measles, mumps, and rubella in the U.S. For instance, measles cases dropped
from about 400,000 cases a year to just 100 in 1999. However, in the developing
world, where kids don't get the vaccine, measles may kill 1 million youngsters
Robert Davis, MD, MPH, of the University of Washington in
Seattle, has recently published a study disputing the link between the MMR
vaccine, bowel disease, and autism. He agrees with the IOM report's
"In medical training, you have children like this die in
your arms from these diseases, and once that happens, you realize that the
vaccine actually prevents things that are very, very serious, and you never
want to see it again," Davis tells WebMD. He says he worries that adverse
publicity about the vaccine will cause parents to avoid it, which is happening
right now in Great Britain.
Still, the idea already resonates among concerned parents:
could the MMR vaccine -- a prerequisite of virtually all U.S. students to enter
school -- pose an autism risk?