A vaccine contains a killed or weakened disease causing microbe that is responsible for infection. Because the germ is killed, it cannot make the person sick. When a person receives a vaccine, the body reacts by producing antibodies in defence. The antibodies remain in the blood for long and destroys the germs of a particular disease. In other words, vaccines expose people safely to germs so that they can fight with the same germs in future against its specific disease.
