The principle of vaccination is to produce immunity against a disease. Explain.

(i) The practice of artificially introducing germs or the germ-substance into a body to develop resistance to specific diseases is called vaccination.

(ii) Scientifically, this practice is termed as prophylaxis and the material introduced into the body is referred to as the vaccine.

(iii) Antibodies form an integral part of our immunity. They destroy unwanted particles that enter the body. The whole aim of vaccines is to signal our immunity to produce specific antibodies. Hence, the principle of vaccination is to produce immunity against a disease.

(iv) The vaccine (containing the germ-substance) that is introduced into the body is usually injected. It can also be delivered orally (like in the case of polio drops).

(v) After the vaccine enters the body, it stimulates the lymphocyte cells to produce antibodies in response to the germs, of the particular disease, that has been injected.