Natural active immunity is acquired through infection.

Natural active immunity is acquired through infection.

• A. True
• B. False
• C. Only after vaccination
• D. Only in adults

Answer: (A)

Natural active immunity develops when the immune system is exposed to a pathogen through infection, not through deliberate antigen exposure. This triggers a primary immune response with B cells making specific antibodies and T cells helping, and crucially, it creates memory B and T cells. Those memory cells persist for years or even a lifetime, so a subsequent encounter with the same pathogen leads to a rapid and stronger secondary response. This type of immunity is different from natural passive immunity, which comes from antibodies transferred from mother to baby, and from artificial active immunity, which is produced by vaccination. It’s not limited to adults—anyone who recovers from an infection can develop natural active immunity.

Natural active immunity develops when the immune system is exposed to a pathogen through infection, not through deliberate antigen exposure. This triggers a primary immune response with B cells making specific antibodies and T cells helping, and crucially, it creates memory B and T cells. Those memory cells persist for years or even a lifetime, so a subsequent encounter with the same pathogen leads to a rapid and stronger secondary response. This type of immunity is different from natural passive immunity, which comes from antibodies transferred from mother to baby, and from artificial active immunity, which is produced by vaccination. It’s not limited to adults—anyone who recovers from an infection can develop natural active immunity.