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Vaccine
Safety > Issues of Interest
How Do Vaccines Protect
Children from Diseases?
Each child is born with a full
immune system composed of cells, glands, organs, and fluids that are
located throughout his or her body to fight invading bacteria and
viruses. The immune system recognizes germs that enter the body as
"foreign" invaders, or antigens, and produces
protein substances called antibodies to fight them. A normal,
healthy immune system has the ability to produce millions of these
antibodies to defend against thousands of attacks every day, doing
it so naturally that people are not even aware they are being
attacked and defended so often (Whitney, 1990). Many antibodies
disappear once they have destroyed the invading antigens, but the
cells involved in antibody production remain and become "memory
cells." Memory cells remember the original antigen and then
defend against it when the antigen attempts to re-infect a person,
even after many decades. This protection is called immunity.
Vaccines contain
the same antigens or parts of antigens that
cause diseases, but the antigens in vaccines
are either killed or greatly weakened. When
they are injected into fatty tissue or muscle,
vaccine antigens are not strong enough to produce
the symptoms and signs of the disease but are
strong enough for the immune system to produce
antibodies against them (Tortora and Anagnostakos,
1981). The memory cells that remain prevent
re-infection when they encounter that disease
in the future. Thus, through vaccination, children
develop immunity without suffering from the
actual diseases that vaccines prevent.
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