Vaccine Benefits, Vaccine Risks: 10 Basic Questions Answered
WebMD News Archive
3. Some autism advocacy groups say vaccines -- especially those that contain the mercury-based compound thimerosal -- can cause autism and brain damage. They are sincerely worried. Why shouldn't I believe them?
"Autism is a serious and very challenging disease for families to cope
with," says Schuchat. "Parents want explanations of how this happened to their
child. lt is important for us to support research and programs that will help
us better understand the factors that lead to autism and to find the best
treatments. But a very large number of scientific studies have been carried
out, and extensive scientific reviews, that have concluded there is no causal
connection between vaccines or the preservative thimerosal and autism.
"There are hundreds of studies that have looked one way or another at these
issues. Some are animal studies, some are toxicology studies, and some are
human studies with a number of different designs. There have been efforts to
review the evidence, the direct human evidence and the indirect animal
evidence. Those reviews don't just look at the last sentence in the article but
look at the study methods and ask if the methods and the results justify the
conclusions. [The most recent]
extensive review was carried out by the Institute of Medicine with a number
of experts and concluded the information from all of these studies taken
together did not support a causal association [between vaccines and
"They concluded that other factors or explanations for autism should be
sought. And more recently, people have thought that genetic and some
environmental research may be more promising than continuing to pursue
(Do you think the MMR vaccine causes autism? WebMD's
Rod Moser, PA, PhD, and
Steven Parker, MD, both say "no." Find out why on their blogs.
4. If only to err on the side of caution, why can't all vaccines be thimerosal-free?
"The vaccines that are given to children in the U.S. are nearly thimerosal
free," says Schuchat. "All but the flu vaccines that are given to young
children do not contain thimerosal. Some formulations of flu vaccine are
thimerosal-free and some are not. So the pediatric vaccine supply is nearly
thimerosal-free. Thimerosal is a preservative that keeps germs from
overgrowing. So vials of vaccine that are multiple doses, 20 or 30 doses, have
a preservative to keep them from bacterial contamination. It was put in there
because people died from vaccines that were contaminated.