What type of immunity does a person gain through natural infection?

When a person gains immunity through natural infection, they develop what's known as active natural immunity. This type of immunity occurs when the body is exposed to a pathogen, such as a virus or bacteria, and the immune system responds by producing its own antibodies and memory cells.

When infected, the immune system activates B cells to produce specific antibodies against the pathogen. Additionally, T cells help identify and eliminate infected cells. This process not only clears the infection but also provides long-lasting protection, as the immune system "remembers" the pathogen for future encounters. This means that if the individual is exposed to the same pathogen again, their immune response will be faster and more robust due to the pre-existing memory cells.

In contrast, passive immunity, such as passive natural immunity, occurs when antibodies are transferred from one individual to another, as seen when a mother passes antibodies to her infant through breast milk. Active artificial immunity involves vaccination, where the immune system is exposed to a harmless form of the pathogen or its components to develop immunity without causing disease. Therefore, the correct characterization of immunity gained through natural infection reflects the concept of active natural immunity.