Editing Vaccination (section)

==Mechanism of function==
[[File:Polio vaccination in Sweden 1957.jpg|thumb|upright=0.8|In Sweden, [[polio vaccination]] started in 1957.]]
[[File:Punkkibussi.jpg|thumb|A mobile medicine laboratory providing vaccinations against diseases spread by [[tick]]s]]
[[File:Anti-COVID-19 Vaccination Center GUMed Gdansk Poland.jpg|thumb|COVID-19 Vaccination Center of the [[Medical University of Gdańsk]], [[Poland]]]]
Vaccines are a way of [[artificial induction of immunity|artificially activating the immune system]] to protect against [[infectious disease]]. The activation occurs through priming the [[immune system]] with an [[immunogen]]. Stimulating immune responses with an infectious agent is known as [[immunization]]. Vaccination includes various ways of administering immunogens.<ref>{{cite journal | vauthors = Kwong PD | title = What Are the Most Powerful Immunogen Design Vaccine Strategies? A Structural Biologist's Perspective | journal = Cold Spring Harbor Perspectives in Biology | volume = 9 | issue = 11 | pages = a029470 | date = November 2017 | pmid = 28159876 | pmc = 5666634 | doi = 10.1101/cshperspect.a029470 }}</ref>

Most vaccines are administered before a patient has contracted a disease to help increase future protection. However, some vaccines are administered after the patient already has contracted a disease. Vaccines given after exposure to smallpox are reported to offer some protection from disease or may reduce the severity of disease.<ref name="CDCvac">{{cite web |url=http://www.bt.cdc.gov/agent/smallpox/vaccination/pdf/vaccine-overview.pdf |title=Vaccine Overview |access-date=2 January 2008 |website=Smallpox Fact Sheet |archive-url=https://web.archive.org/web/20080102234114/http://www.bt.cdc.gov/agent/smallpox/vaccination/pdf/vaccine-overview.pdf |archive-date=2 January 2008 |url-status=dead}}</ref> The first [[rabies]] immunization was given by [[Louis Pasteur]] to a child after he was bitten by a [[Rabies|rabid]] dog. Since its discovery, the rabies vaccine has been proven effective in preventing rabies in humans when administered several times over 14 days along with rabies [[immune globulin]] and wound care.<ref>{{cite journal | vauthors = Rupprecht CE, Briggs D, Brown CM, Franka R, Katz SL, Kerr HD, Lett SM, Levis R, Meltzer MI, Schaffner W, Cieslak PR | display-authors = 6 | title = Use of a reduced (4-dose) vaccine schedule for postexposure prophylaxis to prevent human rabies: recommendations of the advisory committee on immunization practices | journal = MMWR. Recommendations and Reports | volume = 59 | issue = RR-2 | pages = 1–9 | date = March 2010 | pmid = 20300058 }}</ref> Other examples include experimental AIDS, cancer<ref>{{cite journal | vauthors = Oppenheimer SB, Alvarez M, Nnoli J | title = Carbohydrate-based experimental therapeutics for cancer, HIV/AIDS and other diseases | journal = Acta Histochemica | volume = 110 | issue = 1 | pages = 6–13 | date = 2008 | pmid = 17963823 | pmc = 2278011 | doi = 10.1016/j.acthis.2007.08.003 }}</ref> and [[Alzheimer's disease]] vaccines.<ref>{{cite journal | vauthors = Goñi F, Sigurdsson EM | title = New directions towards safer and effective vaccines for Alzheimer's disease | journal = Current Opinion in Molecular Therapeutics | volume = 7 | issue = 1 | pages = 17–23 | date = February 2005 | pmid = 15732525 }}</ref> Such immunizations aim to trigger an immune response more rapidly and with less harm than natural infection.<ref>{{cite journal | vauthors = Irvine DJ, Swartz MA, Szeto GL | title = Engineering synthetic vaccines using cues from natural immunity | journal = Nature Materials | volume = 12 | issue = 11 | pages = 978–90 | date = November 2013 | pmid = 24150416 | pmc = 3928825 | doi = 10.1038/nmat3775 | bibcode = 2013NatMa..12..978I }}</ref>

Most vaccines are given by injection as they are not absorbed reliably through the [[intestines]]. Live attenuated polio, rotavirus, some typhoid, and some cholera vaccines are given orally to produce immunity in the bowel. While vaccination provides a lasting effect, it usually takes several weeks to develop. This differs from [[passive immunity]] (the transfer of [[antibodies]], such as in breastfeeding), which has immediate effect.<ref>{{cite web|url=https://www.cdc.gov/vaccines/vac-gen/immunity-types.htm|title=Immunity Types|publisher=U.S. [[Centers for Disease Control and Prevention]] (CDC)|access-date=20 October 2015|archive-date=22 December 2011|archive-url=https://web.archive.org/web/20111222052748/http://cdc.gov/vaccines/vac-gen/immunity-types.htm|url-status=live}}</ref>

A vaccine failure is when an [[organism]] contracts a disease in spite of being vaccinated against it. Primary [[vaccine]] failure occurs when an organism's immune system does not produce [[antibody|antibodies]] when first vaccinated. Vaccines can fail when several series are given and fail to produce an immune response. The term "vaccine failure" does not necessarily imply that the vaccine is defective. Most vaccine failures are simply due to individual variations in immune response.<ref>{{cite journal | vauthors = Wiedermann U, Garner-Spitzer E, Wagner A | title = Primary vaccine failure to routine vaccines: Why and what to do? | journal = Human Vaccines & Immunotherapeutics | volume = 12 | issue = 1 | pages = 239–43 | date = 2016 | pmid = 26836329 | pmc = 4962729 | doi = 10.1080/21645515.2015.1093263 }}</ref>
[[File:Measles-vaccine-coverage-worldwide-vs-measles-cases-worldwide.png|alt=|thumb|Measles infection rate vs. vaccination rate, 1980–2011. Source: [[World Health Organization|WHO]]]]

===Vaccination versus inoculation===
The term "[[inoculation]]" is often used interchangeably with "vaccination." However, while related, the terms are not synonymous. Vaccination is treatment of an individual with an attenuated (i.e. less virulent) [[pathogen]] or other [[immunogen]], whereas inoculation, also called [[variolation]] in the context of [[smallpox]] prophylaxis, is treatment with unattenuated variola virus taken from a pustule or scab of a smallpox patient into the superficial layers of the skin, commonly the upper arm. Variolation was often done 'arm-to-arm' or, less effectively, 'scab-to-arm', and often caused the patient to become infected with smallpox, which in some cases resulted in severe disease.<ref>{{Cite web|url=http://web.uvic.ca/vv/student/smallpox/doctors/diff.html|title=The Smallpox Epidemic of 1862 (Victoria BC)--Doctors and Diagnosis|website=web.uvic.ca|access-date=29 September 2016|archive-date=2 February 2018|archive-url=https://web.archive.org/web/20180202203718/http://web.uvic.ca/vv/student/smallpox/doctors/diff.html|url-status=live}}</ref><ref>{{cite web |url=http://web.uvic.ca/vv/student/smallpox/doctors/diff.html |title=Doctors and diagnosis ''The difference between Vaccination and Inoculation'' |publisher=Web.uvic.ca |access-date=8 January 2014 |archive-date=2 February 2018 |archive-url=https://web.archive.org/web/20180202203718/http://web.uvic.ca/vv/student/smallpox/doctors/diff.html |url-status=live }}</ref>

Vaccinations began in the late 18th century with the work of [[Edward Jenner]] and the smallpox vaccine.<ref>{{cite news |title=Edward Jenner – (1749–1823) |publisher=Sundaytimes.lk. |date=1 June 2008 |url=http://sundaytimes.lk/080601/FunDay/famous.html |access-date=28 July 2009 |archive-url=https://web.archive.org/web/20110926095825/http://sundaytimes.lk/080601/FunDay/famous.html |archive-date=26 September 2011 |url-status=dead }}</ref><ref>{{cite web |url=https://www.bbc.co.uk/history/historic_figures/jenner_edward.shtml |title=History – Edward Jenner (1749–1823) |publisher=BBC |access-date=1 March 2014 |archive-date=8 March 2021 |archive-url=https://web.archive.org/web/20210308032314/https://www.bbc.co.uk/history/historic_figures/jenner_edward.shtml |url-status=live }}</ref><ref>{{cite web|url=http://www.dinweb.org/dinweb/DINMuseum/Edward%20Jenner.asp|title=Edward Jenner – Smallpox and the Discovery of Vaccination|website=dinweb.org|access-date=22 April 2010|archive-url=https://web.archive.org/web/20100827080455/http://www.dinweb.org/dinweb/DINMuseum/Edward%20Jenner.asp|archive-date=27 August 2010|url-status=dead}}</ref>

===Preventing disease versus preventing infection===

Some vaccines, like the smallpox vaccine, prevent infection. Their use results in [[sterilizing immunity]] and can help eradicate a disease if there is no animal reserve. Other vaccines, including those for {{Nowrap|[[COVID-19]]}}, help to (temporarily) lower the chance of severe disease for individuals, without necessarily reducing the probability of becoming infected.<ref>{{Cite web |url=https://theconversation.com/coronavirus-few-vaccines-prevent-infection-heres-why-thats-not-a-problem-152204 |title=Coronavirus: few vaccines prevent infection – here's why that's not a problem |date=5 January 2021 |last=Caddy |first=Sarah L. |website=[[The Conversation (website)|The Conversation]] |access-date=18 December 2022 |archive-date=18 December 2022 |archive-url=https://web.archive.org/web/20221218103955/https://theconversation.com/coronavirus-few-vaccines-prevent-infection-heres-why-thats-not-a-problem-152204 |url-status=live }}</ref>