Question

Vaccine is an example of

• A. Naturally acquired passive immunity
• B. Naturally acquired active immunity
• C. Artificially acquired passive immunity
• D. Artificially acquired active immunity

Hint:

Remember the four types of acquired immunity:
• Natural Active $\rightarrow$ Infection
• Natural Passive $\rightarrow$ Maternal antibodies
• Artificial Active $\rightarrow$ Vaccination
• Artificial Passive $\rightarrow$ Antiserum or Immunoglobulin injection

Answer 1

The Correct Option is D

Concept: Immunity is the ability of the body to resist infections caused by pathogens. It is broadly classified into innate immunity and acquired (adaptive) immunity. Acquired immunity can further be classified as active or passive, and each may be naturally or artificially acquired.
• Active immunity develops when the body's own immune system produces antibodies after exposure to an antigen.
• Passive immunity is obtained by receiving ready-made antibodies from another source.
• Vaccination introduces weakened, killed or purified antigens into the body.
• These antigens stimulate the immune system to produce antibodies and memory cells without causing the disease.

Step 1: Understand how vaccines work.
Vaccines contain harmless forms of pathogens or their antigens. After vaccination, the immune system recognizes these antigens as foreign and produces specific antibodies and memory B and T cells. \[ \boxed{\text{Vaccine} \longrightarrow \text{Antigen exposure} \longrightarrow \text{Antibody production + Memory cells}} \]

Step 2: Why is it called artificially acquired active immunity?
The immunity is:
• Artificially acquired because the antigen is introduced deliberately through vaccination.
• Active because the individual's own immune system produces antibodies and immunological memory. Thus, vaccination provides long-lasting protection against future infections.

Step 3: Eliminate the incorrect options.

• Naturally acquired passive immunity occurs through maternal antibodies.
• Naturally acquired active immunity develops after natural infection.
• Artificially acquired passive immunity involves injection of ready-made antibodies or antisera. Therefore, \[ \boxed{Option (D) is the correct answer. \]