A vaccine is a special kind of preparation which provides immunity against a particular disease. Vaccine consists dead and weakened microbes which are harmless and do not cause any disease. Vaccine works as follows:

● When the vaccine containing dead or weakened microbes is introduced into the body of a healthy person, the body fights and kills the microbes by producing some substance called antibodies.

● Some of the antibodies remain in the body for a long time and protect it from any future attack of disease germs. Thus, a vaccine develops the immunity from a disease.