Which immune response is characterized by a faster reaction upon second exposure to an antigen?

The adaptive immune response is characterized by its ability to provide a quicker and more effective reaction upon subsequent exposures to the same antigen. This capability is largely due to the formation of memory cells after the first exposure. When the immune system encounters an antigen for the first time, it takes some time to generate a specific immune response, during which B-cells and T-cells adapt to the pathogen and create memory cells that remember this interaction.

Once the body is re-exposed to the same antigen, these memory cells can rapidly recognize and respond to the pathogen. This leads to a faster and more robust immune response, often preventing illness or significantly reducing the severity of symptoms. This efficiency is a crucial feature of the adaptive immune system, differentiating it from other responses like the innate immune response, which reacts instantly but lacks memory, or the inflammatory and allergic responses, which pertain to different mechanisms of immune activity.