How do vaccine works?

Vaccine consists of a biological agent. Regards of whether target bacteria or viruses, vaccine work by stimulating the body natural defenses by teaching the immune system to identify the infectious agent in order to neutralize it. Vaccine also does refresh the immune systems’ memory, so that in the future it will be able to recognize viruses and bacteria.

Immune system is an internal army, made up of millions of different kinds of solider-cells such us lymphocytes, macrophages, and specialized molecules such as antibodies.  The internal army locates and destroys any infectious agent that enters the body. When foreign agent invaders such as bacteria or viruses enter the body, the immune cells called lymphocytes respond by producing antibodies (protein molecules) to fight the invader and protect the body against further infection.