page_title: Immunity (medical)
section_title: Artificially acquired
hierarchical_section_title: Immunity (medical) / Active / Artificially acquired
context_page_description: In biology, immunity is the capability of multicellular organisms to resist harmful microorganisms. Immunity involves both specific and nonspecific components. The nonspecific components act as barriers or eliminators of a wide range of pathogens irrespective of their antigenic make-up. Other components of the immune system adapt themselves to each new disease encountered and can generate pathogen-specific immunity.
context_section_description: Artificially acquired active immunity can be induced by a vaccine, a substance that contains antigen. A vaccine stimulates a primary response against the antigen without causing symptoms of the disease. Richard Dunning coined the term vaccination, a colleague of Edward Jenner, and adapted by Louis Pasteur for his pioneering work in vaccination. The method Pasteur used entailed treating the infectious agents for those diseases, so they lost the ability to cause serious disease. Pasteur adopted the name vaccine as a generic term in honor of Jenner's discovery, which Pasteur's work built upon.
  In 1807, Bavaria became the first group to require that their military recruits be vaccinated against smallpox, as the spread of smallpox was linked to combat. Subsequently, the practice of vaccination would increase with the spread of war.
  There are four types of traditional vaccines:
  Inactivated vaccines are composed of micro-organisms that have been killed with chemicals and/or heat and are no longer infectious. Examples are vaccines against flu, cholera, plague, and hepatitis A. Most vaccines of this type are likely to require booster shots.
  Live, attenuated vaccines are composed of micro-organisms that have been cultivated under conditions which disable their ability to induce disease.  These responses are more durable, however, they may require booster shots. Examples include yellow fever, measles, rubella, and mumps.
  Toxoids are inactivated toxic compounds from micro-organisms in cases where these (rather than the micro-organism itself) cause illness, used prior to an encounter with the toxin of the micro-organism.  Examples of toxoid-based vaccines include tetanus and diphtheria.
  Subunit vaccines, recombinant, polysaccharide, and conjugate vaccines are composed of small fragments or pieces from a pathogenic (disease-causing) organism. A characteristic example is the subunit vaccine against Hepatitis B virus.
  Two future vaccinations:
  DNA vaccines: DNA vaccines are composed of DNA encoding protein antigens from the pathogen. These vaccines are inexpensive, relatively easy to make and generate a strong, long-term immunity.
  Recombinant vector vaccines (platform-based vaccines): These vaccines are harmless live viruses that encode a one/or a few antigens from a pathogenic organism. They are used widely in veterinary medicine.
  Most vaccines are given by hypodermic or intramuscular injection as they are not absorbed reliably through the gut.  Live attenuated polio and some typhoid and cholera vaccines are given orally in order to produce immunity based in the bowel.
caption: Poster from before the 1979 eradication of smallpox, promoting vaccination.
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