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The immune responses of our body
cannot prevent diseases but they help the body recover from
diseases. When the body is exposed to a disease for the first time,
it takes some time for the immune response to work at helping the
body recover. Repeated attacks of the same disease will, however, be
dealt with more quickly. In fact, when the disease attacks
repeatedly, the body’s immune system can actually prevent the
disease before any symptoms appear. Eventually the body develops
complete resistance to the disease. This complete resistance may be achieved through either
active or passive immunization.
Active immunization is the term
used to describe the condition when a person’s own immune system
is activated and an immune response is generated. Active
immunization can be achieved either by natural immunization or by
vaccination.
A person develops natural
immunization during childhood. Diseases such as chickenpox, which generally occur during
childhood, never occur again because the immune system develops
lifelong resistance to it.
Vaccination is immunization that is
induced intentionally. This
is done by the use of vaccines. Vaccines are substances that have a
structure similar to disease producing agents. Vaccines are
introduced into the body but, unlike the disease-producing agents,
they do not produce the disease in the body despite being
structurally similar to the disease-producing agents. Vaccines such
as the ones as for tetanus and whooping cough contain chemically
killed bacteria or other pathogenic organisms. The other type of
vaccine, like the oral polio vaccine, contains weakened forms of
living organisms that have been genetically selected so that they do
not produce disease.
Passive
immunization is another way of preventing diseases. Here, a person
receives antibodies that are created in another person or animal.
This method is generally used when natural immunization
cannot be used or when the natural immunization process is much
slower than the rate at which the disease is spreading. This method
however has some disadvantages, the main one being that the effect
of the vaccine is temporary. Repeated
use of passive immunization is, however, not advisable.
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