Autism-Vaccine Link: Evidence Doesn't Dispel Doubts
Many major medical groups say vaccines don't cause autism. Many parents say they do. So who's right?
Vaccines and Autism: Other Studies Under Way continued...
The Childhood Autism
Risks From Genetics and the Environment (CHARGE) study is under way at the
University of California, Davis. Funded by the National Institute of
Environmental Health Sciences and enrolling more than 600 families with autism,
this study is looking at the interplay between genetic and a wide range of
environmental factors in autism. Vaccines are one of the many environmental
factors being analyzed.
In addition, the
CDC's Centers for Autism and Developmental Disabilities Research and
Epidemiology network (CADDRE) is collecting data on environmental risk factors,
including vaccines, that might put children at risk of autism.
Using the same
environmental-factor checklist as CHARGE and CADDRE, the NIMH is looking at
differences between children with regressive autism and children with more
classic forms of autism.
"We are looking
at differences in environmental exposures, including vaccines but also
including things like older brothers who had a cold and mothers who drank a lot
of diet soda during pregnancy," Swedo says.
The CDC and the NIH are also
performing epidemiologic studies in Norway and Denmark to expand previous
research into whether vaccinated children have any more autism than
"Neither [NIMH Director Tom]
Insel or I are ready to discard the vaccine hypothesis, but we don't think
there is anything in vaccines that causes autism in the vast majority of
cases," Swedo tells WebMD. "In earlier cases where vaccines caused rare
complications, we figured it out quickly. Since vaccines are given so often, if
there was a strong connection between vaccination and autism we would know it
by now. What we are not discarding is the one-in-ten-thousand or
one-in-a-million cases that might have a link."
Vaccines and Autism: High Stakes
The specter of autism frightens parents. But today few parents in the U.S.
or other developed countries have seen the suffering and death wrought by
measles and other disease that vaccines can prevent, including measles,
tetanus, polio, diphtheria, whooping cough, and influenza. These diseases still
afflict millions of children in places that vaccines don't reach.
Every year, 2.5 million unvaccinated children worldwide die of diseases that
vaccines could have prevented, and vaccines prevent the deaths of an additional
2 million children, according to the World Health Organization.