Active Immunity:

(i) It is developed when person's own cells produce antibodies in response to infection or vaccine.

(ii) Immunity is not immediate. A time lapse occurs for its development.

(iii) It lasts for sufficiently long period, may be life long.

(iv) It has no side effects.

(v) Examples - Bacterial vaccines, viral vaccines, bacterial products such as toxoids for diphtheria and tetanus.

Passive Immunity:

(i) It is developed when antibodies produced in other organisms are injected into a person to counteract antigen.

(ii) Immunity develops immediately.

(iii) It is not long lasting.

(iv) At times, the body reacts to the introduction of antisera. It is called serum sickness.

(v) Examples - Human colostrum containing IgC antibodies, antitetanus serum (ATS), anti diphtheritic serum (ADS), anti-gas gangrene serum (AGS).