What does it do ?

The human immune system is designed to protect us from anything
that enters our body that doesn't belong there. When a disease organism enters
the body, the immune system recognizes it and produces
proteins called antibodies to get rid of it. These antibodies find and
destroy the specific germ that is causing the infection.
But in addition, the immune system remembers this germ. Later on, if
the person is exposed to the same germ again, antibodies are quickly
deployed to eliminate it before it can make the person sick again. This
is immunity.However it can take a week before you start to feel better
This problem is solved by vaccines. Vaccines contain the same germs
that cause disease (for example, measles vaccine contains measles
virus, and Hib vaccine contains Hib bacteria). But they have been
either killed, or weakened to the point that they don’t make you sick.
Some vaccines contain only a part of the disease germ.
When a child is vaccinated, the vaccine stimulates his immune system
to produce antibodies, exactly like it would if he were exposed to the
disease. The child will develop immunity to that disease, and best of
all he doesn’t have to get sick first.This is what makes vaccines such powerful medicine. Unlike most medicines, which treat or cure diseases, vaccines prevent them.