NCERT · Class 12 · Biology · Human Health and DiseasesExplain the key differences between Active Immunity and Passive Immunity.

Active immunity is the type of acquired immunity developed when a host organism's own immune system is exposed to living or dead microbes or foreign antigens, leading to the self-production of antibodies. It is slow and takes time to give its full effective response, but provides long-lasting protection with memory (e.g., vaccination). In contrast, passive immunity is conferred when ready-made or pre-formed antibodies are directly injected or transferred into the body to protect against foreign agents, providing immediate but short-lived protection without forming memory cells (e.g., colostrum containing IgA).