March 6, 2008 -- What are the real benefits -- and the real risks -- of U.S.
childhood vaccines? Do vaccines cause autism? Why do some vaccines still
contain the controversial, mercury-based compound thimerosal? WebMD went to
experts for the answers to some frequently asked questions:
"Vaccines help our bodies make protection against life-threatening
infectious diseases," says Anne Schuchat, MD, director of the CDC's National
Center for Immunization and Respiratory Diseases.
When a germ invades the body, the immune system recognizes it as a foreign
invader. This sets off a cascade of events. The immune system makes antibodies,
which are specialized molecules that stick to the invader and either inactivate
it or mark it for destruction. Specialized immune cells also seek out and
destroy germs and cells in which germs are multiplying. Other immune cells
remember the germ so the next time a germ of the same kind tries to invade the
body, the immune system will be able to mount an immediate response.
Vaccines offer a shortcut to immunity by raising protective immune responses
before a germ invades. This gives the body a crucial head start that lets it
prevent dangerous infections or make them less severe.
2. I heard that the U.S. government says childhood vaccinations might cause autism and something called mitochondrial disease. Is this true?
In March 2008, the Division of Vaccine Injury Compensation (DVIC) at the
Department of Health and Human Services agreed there is a possibility that
vaccination "aggravated an underlying mitochondrial disorder" in a young girl.
The girl suffered "a regressive encephalopathy with features of autism spectrum
disorder" after receiving five standard childhood vaccines in July 2000. The
DVIC agreed that the girl and her family should be compensated.
Mitochondria are the energy-making structures inside the cells of our
bodies. They have their own DNA, which we inherit directly from our mothers.
Mitochondrial diseases or disorders are caused by defects in mitochondrial DNA,
or by defects in regular DNA that affect mitochondrial function.
People with mitochondrial disease may get too little energy to power the
immune system, the nervous system, and/or other important bodily functions. Or
their dysfunctional mitochondria allow toxins to build up within cells.
The case settled by the DVIC is a legal case, not a scientific study. The
DVIC agreed only that it is biologically plausible for a girl with a
mitochondrial disorder to have been injured by her vaccination. The DVIC did
not say that vaccines cause autism.
Does vaccination truly aggravate mitochondrial disease? WebMD asked Chuck
Mohan, executive director and CEO of the United Mitochondrial Disease
"There is no scientific proof that vaccines cause mitochondrial disease or
autism, but there is very little scientific research in this area," Mohan says.
"Persons with mitochondrial disease don't necessarily have autism, and persons
with autism don't necessarily have mitochondrial disease. The tie-in is that in
this case, mitochondrial disease was exacerbated by vaccination."