Vaccines: Are the
Shots Safe?
By Alice
Park
Ask the parents of autistic children whether they believe
childhood vaccines can cause autism, and the answer will probably
be yes. They have heard of too many cases of babies who were
perfectly normal until they got their measles, mumps and rubella
(MMR) shot and then within weeks — if not days —
started throwing tantrums, losing language skills and generally
tuning out.
Ask doctors the same question, and they are likely to cite
the panel of experts convened by the Institute of Medicine
last year. It studied the evidence but found no explanation
for how vaccines might possibly cause autism. Included in
the review were studies that showed no significant difference
in the incidence of autism disorders before and after MMR
immunization became routine in 1988 in the United Kingdom.
"We bent over backward to look for the biological mechanisms
that would support a link," says the panel's chairwoman, Dr.
Marie McCormick of the Harvard School of Public Health.
But failing to prove that something can happen is not the
same as proving it doesn't, and the issue is still a matter
of furious debate. The only scientific evidence against childhood
vaccines comes from Dr. Andrew Wakefield, formerly at the
Royal Free Hospital in London. His theory is that autism stems
from a severe immune reaction to something in the vaccine.
In February he published a paper showing that immunized children
with autism and bowel disorders have higher levels of measles
particles in their intestinal tissue than normal children
do. The evidence is not entirely persuasive, however; measles
particles in the tissues do not necessarily mean that the
virus — or the vaccine — causes autism.
What about all the children whose symptoms appeared shortly
after their MMRs? The association may be purely coincidental.
The shots are given at 15 months, which is when behavior and
speech patterns in babies usually become sufficiently pronounced
for parents to start noticing that something is wrong. Most
of the evidence suggests that autism is primarily a genetic
disorder. It may be that some symptoms appear immediately
after birth but are too subtle to be spotted in the first
year or so of life.
To get more definitive answers, the National Institutes of Health
and the Centers for Disease Control have each launched their
own investigations. Karyn Seroussi of Poughkeepsie, N.Y., for
one, supports this research. "If it's the shots, I want to know,"
says the autism advocate and parent of an autistic son. "If
it's not, I want to know what the heck it is that's causing
autism." On that, both parents and doctors can agree.
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