Immune System

Our immune system has a type of memory as well. When one fights an infection, the immune system will produce an antibody to fight the foreign invader into the person's body. If reintroduced into the body, our immune system will be able to recognize the intruder and destroy it with the antibody produced previously. That is why people rarely get chicken pox more than once. It is also how vaccines work. When one gets a vaccination shot, a very small portion of the illness is being injected into his or her body. The amount is small enough so that it doesn't get you sick, but large enough so that your immune system should detect it and start making cells that will recognize and attack ones like it in the future.