Most of the vaccines consist of non virulent, mutant strains of the poliovirus. The use of vaccines, which stimulate the production of antibodies in the body, and making a person immune against the disease or infection, is called active immunity. Active immunity response is not immediately available but it is long lasting.
Artificially induced immunity:
The active immunity that has been achieved by artificially introducing, antigen in the body, is called artificially induced active immunity.
Naturally induced immunity:
But, when a person is exposed to an infection (antigen) becomes ill, and in most cases survives the immunity, developed against that disease is called naturally induced immunity or auto immune response.
When antibodies are injected in the form of antisera, to make a person immune against a disease, it is called passive immunity.
Passive immunity response is immediate, but not long lasting. Because no time is taken for the production of sufficient level of antibodies,(as antibodies are being injected) and after the level of antibodies is reduced or they are used up-No more antibodies production is there.
The method of passive immunization is used to combat active infections of, tetanus, infections hepatitis, rabies, snake bit venom etc. In the case of snake bite venom passive immunity is produced by the antitoxin so the serum is called antivenom serum.