- Naturally acquired active immunity: Occurs after exposure to the antigen; long-term resistance results, due to the events of a primary immune response
- Naturally acquired passive immunity: Occurs as antibodies are passed from mother to fetus; this is short term immunity, due to lack of an immune response and lack of memory BCell formation
- Artificially active immunity: Occurs through the use of vaccines, without the person becoming I'll from the disease; since vaccines contain weakened or dead pathogens, person develops long term immunity, due to an immune response that includes memory B Cell formation
- Artificially passive immunity: involves the injection of gamma globulins containing antibodies or antiserum; this is short term, cause there was no antigen exposure, no immune response and no memory BCell produced.