7 November 2002
Finds No Link Between MMR Vaccine and Autism
Danish researchers say results are relevant in trying to understand
rise in U.S. cases.
By Rosie Mestel, Times Staff Writer
of 500,000 Danish children has found no link between receiving
the measles-mumps-rubella vaccine and developing the devastating
childhood disorder known as autism.
study, published today in the New England Journal of Medicine, is
the latest of several studies to negate the suspicion, held by many
parents, that the MMR vaccine is behind the recent dramatic rise
in autism cases. In California, the number of autistic children
receiving services from the state's Department of Developmental
Services climbed 273% between 1987 and 1998.
the study is from Denmark, it is relevant for the United States,
the authors said. The two countries use the same MMR vaccine and
use very similar medical criteria for diagnosing autistic children.
studies had concluded there is no evidence of a MMR-autism link.
But several scientists said the study was particularly powerful
because it was so large and allowed researchers to track children
residents of Denmark are given an identification number, and later
medical events such as vaccinations and psychiatric diagnoses are
study, led by epidemiologist Dr. Kreesten Meldgaard Madsen of the
Danish Epidemiology Science Center, analyzed data for all Danish
children born between January 1991 and December 1998.
those 537,303 children, 440,655 had received an MMR vaccine and
96,648 had not. A total of 316 had been diagnosed with autistic
disorder, and 422 had been diagnosed with other, closely related
conditions collectively known as autism spectrum disorders.
the data, the scientists found that children who had been vaccinated
were statistically no more likely to develop autism than children
who had not been vaccinated.
study was co-authored by scientists at the Danish center in Aarhus
and Copenhagen, and the U.S. Centers for Disease Control and Prevention
hope the study finally lays to rest the idea that the MMR vaccine
causes autism," said Dr. Jay M. Lieberman, chief of pediatric
infectious diseases at Miller Children's Hospital in Long Beach.
Lieberman said that he has been troubled by an increase in the numbers
of parents refusing the MMR vaccination out of fears that it will
hurt their children.
kills about 600,000 people worldwide each year, Lieberman said.
It killed more than 140 people in the United States during a 1989-91
outbreak caused by inadequate vaccination among schoolchildren.
Rubella causes birth defects when it infects pregnant women, and
was once a leading cause of deafness in the U.S. before MMR vaccinations
are still seeking an explanation for the apparent rise in autism
cases. They know that genetics is involved -- autism tends to run
in families -- and have narrowed down the location of some of the
possible genes. Because the rate of the disorder appears to have
risen, scientists are also investigating possible environmental
factors such as exposure to thimerosal, a mercury-based preservative
used in some vaccines. The MMR vaccine does not contain thimerosal.
many scientists still suspect that at least some of the seeming
rise is due to increased diagnosis instead of an actual increase.
Parents, teachers and doctors are all far more aware of autism than
in years past, said Catherine Lord, professor of psychology and
psychiatry at the University of Michigan.
recent UC Davis study concluded that the steep increase in California
cases could not be explained in this fashion. Until larger-scale
surveys are undertaken, "I think we just don't know,"
activists who strongly suspect an MMR-autism link say the Danish
study still does not lay the matter to rest.
not at all convinced by it," said Bernard Rimland, director
of the Autism Research Institute in San Diego.
said that rates of autism in the Danish study were lower than those
in the U.S., leading him to suspect that data could not be extrapolated
to the U.S. situation.
Birt, a Chicago-based activist and mother of an autistic child,
said the study was flawed because it did not look at the effect
of the MMR vaccine on a certain type of autism that she believes