Editing Immunization (section)

{{Short description|Process by which an individual's immune system becomes fortified against an infectious agent}}
{{For|financial immunization|Immunization (finance)}}

[[File:Typhoid inoculation2.jpg|thumb|Dr. Schreiber of San Augustine giving a [[typhoid inoculation]] at a rural school, [[San Augustine County, Texas]]. Transfer from [[U.S. Office of War Information]], 1944.]]
'''Immunization''', or '''immunisation''', is the process by which an individual's [[immune system]] becomes fortified against an [[infectious agent]] (known as the [[antigen|immunogen]]). When this system is exposed to [[molecule]]s that are foreign to the body, called ''non-self'', it will orchestrate an immune response, and it will also develop the ability to quickly respond to a subsequent encounter because of [[immunological memory]]. This is a function of the [[adaptive immune system]]. Therefore, by exposing a human, or an animal, to an immunogen in a controlled way, its body can learn to protect itself: this is called active immunization. The most important elements of the immune system that are improved by immunization are the [[T cell]]s, [[B cell]]s, and the [[Antibody|antibodies]] B cells produce. [[Memory B cell]]s and [[memory T cell]]s are responsible for a swift response to a second encounter with a foreign molecule. [[Passive immunization]] is direct introduction of these elements into the body, instead of production of these elements by the body itself.

Immunization happens in various ways, both in the [[wildness|wild]] and as done by human efforts in [[health care]]. [[Immunity (medical)#Naturally acquired|Natural immunity]] is gained by those organisms whose immune systems succeed in fighting off a previous infection, if the relevant pathogen is one for which immunization is even possible. Natural immunity can have degrees of effectiveness (partial rather than absolute) and may fade over time (within months, years, or decades, depending on the pathogen). In health care, the main technique of [[artificial induction of immunity]] is [[vaccination]],<ref>{{cite web | url=https://medlineplus.gov/immunization.html | title=Vaccines | access-date=2020-04-02 | archive-date=2020-11-14 | archive-url=https://web.archive.org/web/20201114000938/https://medlineplus.gov/immunization.html | url-status=live }}</ref> which is a major form of [[preventive healthcare|prevention of disease]], whether by prevention of infection (pathogen fails to mount sufficient reproduction in the host), prevention of severe disease (infection still happens but is not severe), or both. Vaccination against [[vaccine-preventable diseases]] is a major relief of [[disease burden]] even though it usually cannot eradicate a disease. Vaccines against [[microorganism]]s that cause [[disease]]s can prepare the body's immune system, thus helping to fight or prevent an [[infection]]. The fact that [[mutation]]s can cause [[cancer]] [[Cell (biology)|cells]] to produce proteins or other molecules that are known to the body forms the theoretical basis for therapeutic [[cancer vaccine]]s. Other molecules can be used for immunization as well, for example in experimental vaccines against [[nicotine]] ([[NicVAX]]) or the hormone [[ghrelin]] in experiments to create an obesity vaccine.

Immunizations are often widely stated as less risky and an easier way to become immune to a particular disease than risking a milder form of the disease itself. They are important for both adults and children in that they can protect us from the many diseases out there. Immunization not only protects children against deadly diseases but also helps in developing children's immune systems.<ref>{{cite web | url=http://vaxins.in/blog/child-vaccinations/ | title=Top Vaccination For Your Child | publisher=Vaxins | access-date=29 July 2016 | archive-date=15 August 2016 | archive-url=https://web.archive.org/web/20160815014307/http://vaxins.in/blog/child-vaccinations/ | url-status=dead }}</ref> Through the use of immunizations, some infections and diseases have almost completely been eradicated throughout the World.  One example is [[polio]]. Thanks to dedicated health care professionals and the parents of children who vaccinated on schedule, polio has been eliminated in the U.S. since 1979. Polio is still found in other parts of the world so certain people could still be at risk of getting it. This includes those people who have never had the vaccine, those who did not receive all doses of the vaccine, or those traveling to areas of the world where polio is still prevalent. Active immunization/vaccination has been named one of the "Ten Great Public Health Achievements in the 20th Century".