Immunization

Immunization against infectious agents to induce a specific, protective immune response can be achieved actively or passively.Passive immunization is the administration of preformed protective antibodies; this immunity is short lived. Active immunization involves the administration of antigens to induce humoral and/or cell-mediated immune responses to a specific micro-organism; this provides more enduring immunity. The first description of active immunization is attributed to Edward Jenner, who, in 1796, induced protective immunity to smallpox by inoculating cowpox (vaccinia) vesicle fluid into the skin of susceptible individuals, though inoculation against smallpox was a Middle Eastern technique that had already been publicized in Western Europe by Lady Mary Wortley Montagu (1689–1762). The successful global eradication of smallpox in the late 1970s is testament to the efficacy of immunization in controlling the spread of infectious diseases. There are now many vaccines in routine use, to prevent the major infectious diseases of childhood and to protect against infections encountered through travel or occupational exposure. Other vaccines are under-developed, and new techniques are being exploited to produce vaccines with enhanced efficacy and reduced toxicity.