Immunity is the state of being immune to disease. Infection with a disease organism or exposure to its toxin triggers the body to make antibodies against it. When you have antibodies against a particular disease, your immune system will recognize that pathogen and quickly attack it, which helps prevent infection.
Like a security system that detects intruders and sounds the alarm, your immune system consists of organs, cells and proteins that work together to locate and eliminate germs and other invaders that threaten your health. It also heals the damage that intruders cause.
Your first line of defense is the innate immune system, which is active from the moment you’re born. It includes physical barriers, such as the skin and the mucous membrane that lines the respiratory, gastrointestinal and genitourinary tracts. It also includes a series of soluble factors and phagocytic cells that act as the immediate response to any pathogens that manage to bypass the physical barriers.
The innate immune system works in conjunction with the adaptive immune system, which is your natural ability to learn and remember how to fight specific diseases. It is based on the principle that once your immune system has successfully attacked a particular disease, it will automatically recognize that disease again in the future, allowing it to mount an attack more quickly and effectively.
This type of immunity occurs through either natural or vaccine-induced immunological memory. The former develops when the immune system is exposed to a disease organism, such as an actual infectious illness or to a killed or weakened form of a disease organism, such as through vaccination. The latter results when a disease organism or toxin is introduced into the body through vaccination, triggering the immune system to produce antibodies against it.