Is
there a link between autism and
childhood vaccines ?
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The
National Vaccine Advisory
Committee has recommended that
new studies be done to evaluate
vaccine safety, including
additional study of the
potential vaccine-autism link.
We have learned a great deal
about autism in the past decade
or so. There is a genetic
component to autism, yet it is
not from a single gene. Autism
and autism spectrum disorder are
called "polygenic" diseases,
meaning
that multiple genes have been
shown to be associated with
these diseases.
Studies have also clearly shown
that there is an environmental
component, i.e., "a trigger",
that is required. What this
means is that some children have
a genetic predisposition so that
when they experience some stress
or damage they develop autism,
while children without this
genetic predisposition who are
exposed to the same stress or
damage do not develop autism.
Vaccines are an obvious
potential environmental trigger
for autism.
Childhood vaccination programs
were introduced to the US about
1970. Before this we didn't
vaccinate our children widely,
because vaccines other than
smallpox and polio, were not
available. Between 1970 &
1985 about
60% of US children were
vaccinated for mumps, measles
and rubella (MMR). Nationwide
vaccination campaigns brought
that rate up to over 90% by the
mid-1990's.
In 1979 a new version of the MMR
vaccine was introduced to the
US, and by 1983 only the new
version was available. At the
same time, autism began rising
in the US after 1979 and spiked
up dramatically between 1983 and
1990 from 1 in 10,000 children
to 1 in 500. Autism cannot
usually be diagnosed until a
child is at least 3 years old,
so the gap between the 1979
introduction of the new vaccine
and the 1983 first spike in
autism diagnosis is compelling.
In 1988, this new version of the
MMR vaccine used in the US was
also introduced to the UK.
Autism then spiked up
dramatically in the UK.
The association between the
introduction of the new MMR
vaccine and autism rates,
separated by a decade
in the US and the UK, was what
led scientists to first suspect
that vaccines, particularly the
new MMR vaccine, might be
associated with autism. Studies
done to examine potential links
between vaccines and autism have
focused on the measles virus in
this new MMR vaccine and on the
presence of mercury (Thimerosal)
in vaccines.
However,
in some countries mercury was
completely removed from
vaccines as early as 1993, yet
autism rates have continued to
increase in those countries.
The
scientific community has done
careful, detailed studies that
indicate mercury in vaccines
is not a trigger for autism.
While the pharmaceutical
industry would like to conclude
that vaccines are not the
environmental trigger for
autism, the association between
the new vaccine versions and
autism is too compelling for
parents and grandparents to
ignore, and real-life experience
continues to implicate vaccines
as a trigger for autism in some
way. But
what is in the vaccines that
could be a trigger for autism?
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