Active immunization is the induction of immunity after exposure to an antigen. Antibodies are created by the recipient and may be stored permanently.
Active immunization can occur naturally when a microbe or other antigen is received by a person who has not yet come into contact with the microbe and has no pre-made antibodies for defense. The immune system will eventually create antibodies for the microbe, but this is a slow process and, if the microbe is deadly, there may not be enough time for the antibodies to begin being used.
Artificial active immunization is where the microbe is injected into the person before they are able to take it in naturally. The microbe is treated, so that it will not harm the infected person. Depending on the type of disease, this technique also works with dead microbes, parts of the microbe, or treated toxins from the microbe.
Famous quotes containing the word active:
“The sense of an entailed disadvantage—the deformed foot doubtfully hidden by the shoe, makes a restlessly active spiritual yeast, and easily turns a self-centred, unloving nature into an Ishmaelite. But in the rarer sort, who presently see their own frustrated claim as one among a myriad, the inexorable sorrow takes the form of fellowship and makes the imagination tender.”
—George Eliot [Mary Ann (or Marian)