Vaccination - Mechanism of Function

Mechanism of Function

In the generic sense, the process of artificial induction of immunity, in an effort to protect against infectious disease, works by 'priming' the immune system with an 'immunogen'. Stimulating immune response, via use of an infectious agent, is known as immunization. Vaccinations involve the administration of one or more immunogens, which can be administered in several forms.

Some vaccines are administered after the patient already has contracted a disease. Vaccinia given after exposure to smallpox, within the first three days, is reported to attenuate the disease considerably, and vaccination up to a week after exposure likely offers some protection from disease or may modify the severity of disease. The first rabies immunization was given by Louis Pasteur to a child after he was bitten by a rabid dog. Subsequent to this, it has been found that, in people with uncompromised immune systems, four doses of rabies vaccine over 14 days, wound care, and treatment of the bite with rabies immune globulin, commenced as soon as possible after exposure, is effective in preventing the development of rabies in humans. Other examples include experimental AIDS, cancer and Alzheimer's disease vaccines. The essential empiricism behind such immunizations is that the vaccine triggers an immune response more rapidly than the natural infection itself.

Most vaccines are given by hypodermic injection as they are not absorbed reliably through the intestines. Live attenuated polio, some typhoid and some cholera vaccines are given orally to produce immunity based in the bowel.