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VACCINATION
The immune system can develop long-term immunity to some diseases: this property has been used to develop vaccines, which induce active immunity. Vaccination (vaccination/vaccinazione/vacunación) [I1],[I2],[E1],[E2],[F],[ES],is a term derived from Latin “vacca” (cow, after the cowpox material used by Edward Jenner in the first vaccination). Vaccines are made out of dead pathogens or weakened strains of viruses or bacteria that prompt the development of antibodies in the body and stimulate the formation of memory cells without causing the disease. The goal of all vaccines is to promote a primary immune reaction so that when the organism is again exposed to the antigen, a much stronger secondary immune response will be elicited, with a shorter lag time, a more rapid buildup, a higher overall level of response, a more specific or better "fit" to the invading antigen, and the production of IgG instead of the large multipurpose antibody IgM. The design of immunizing vaccines is based on the specificity and cross-reactivity of the antibody-antigen bonds. The more specific the bond, the more effective and long-lived the vaccine. For example, the smallpox vaccine is 100% effective and provides immunity for about 20 years, whereas vaccines for cholera do not protect against all forms of the disease and protect for less than a year. Biotechnology applications allow development of even safer vaccines.
Passive immunity is the type of immunity involved when the individual is given antibodies to fight a specific disease; passive immunity is short-lived.
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