Redigerer Reproduksjonstall (avsnitt)

== Epidemiologi ==
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|+ Anslått ''R''<sub>0</sub> for kjente sykdommer <ref name="Smallpox">Unless noted ''R<sub>0</sub>'' values are from [https://stacks.cdc.gov/view/cdc/27929 History and Epidemiology of Global Smallpox Eradication] ({{webarchive|url=https://web.archive.org/web/20160510161824/http://emergency.cdc.gov/agent/smallpox/training/overview/pdf/eradicationhistory.pdf|dato=10.05.2016}}), a module of the training course "Smallpox: Disease, Prevention, and Intervention". The CDC and the [[World Health Organization]], 2001. Slide 17. This gives sources as "Modified from ''[[Epidemiologic Reviews|Epid Rev]]'' 1993;15: 265-302, ''[[American Journal of Preventive Medicine|Am J Prev Med]]'' 2001; 20 (4S): 88-153, ''[[Morbidity and Mortality Weekly Report|MMWR]]'' 2000; 49 (SS-9); 27-38"</ref>
! Sykdom !! Smittemetode !! R<sub>0</sub>
|-
| [[Meslinger]] || [[luftbåren smitte|luftbåren]] || 12–18<ref>{{cite journal |last1=Guerra |first1=Fiona M. |last2=Bolotin |first2=Shelly |last3=Lim |first3=Gillian |last4=Heffernan |first4=Jane |last5=Deeks |first5=Shelley L. |last6=Li |first6=Ye |last7=Crowcroft |first7=Natasha S. |title=The basic reproduction number (R0) of measles: a systematic review |journal=The Lancet Infectious Diseases |dato=1. desember 2017 |volume=17 |issue=12 |pages=e420–e428 |doi=10.1016/S1473-3099(17)30307-9 |url=https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(17)30307-9/fulltext |language=engelsk |issn=1473-3099}}</ref>
|-
| [[Vannkopper]] (varicella) || luftbåren || 10–12<ref>{{cite book |author1=Ireland's Health Services  | title = Health Care Worker Information | url = https://www.hse.ie/eng/health/immunisation/hcpinfo/guidelines/chapter23.pdf }}</ref>
|-
|[[SARS-CoV-2 Delta-varianten|Covid-19, Delta]]
|Dråper i luft
|3-8 <ref>{{Kilde www|url=https://context-cdn.washingtonpost.com/notes/prod/default/documents/54f57708-a529-4a33-9a44-b66d719070d9/note/753667d6-8c61-495f-b669-5308f2827155.|tittel=Improving communications around vaccine breakthrough and vaccine effectiveness|besøksdato=18.08.2021|forfattere=cdc.gov|dato=29.07.2021|forlag=cdc.gov|sitat=Delta variant is as transmissible as: - Chicken Pox|arkiv-dato=2021-08-11|arkiv-url=https://web.archive.org/web/20210811184943/https://context-cdn.washingtonpost.com/notes/prod/default/documents/54f57708-a529-4a33-9a44-b66d719070d9/note/753667d6-8c61-495f-b669-5308f2827155.|url-status=yes}}</ref><ref>{{Kilde www|url=https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-variant.html|tittel=Coronavirus Disease 2019 (COVID-19)|besøksdato=2021-08-18|dato=2020-02-11|etternavn=CDC|språk=en-us|verk=Centers for Disease Control and Prevention}}</ref><ref>{{Kilde www|url=https://www.nationalgeographic.com/science/article/why-is-delta-more-infectious-and-deadly-new-research-holds-answers|tittel=Why is Delta more infectious and deadly? New research holds answers.|besøksdato=2021-08-18|dato=2021-08-06|språk=en|verk=Science}}</ref><ref>{{Kilde www|url=https://health-desk.org/articles/how-contagious-is-the-delta-variant-compared-to-other-infectious-diseases|tittel=How contagious is the Delta variant compared to other infectious diseases?|besøksdato=2021-08-18|språk=en|verk=health-desk.org}}</ref><ref>{{Kilde artikkel|tittel=The reproductive number of the Delta variant of SARS-CoV-2 is far higher compared to the ancestral SARS-CoV-2 virus|publikasjon=Journal of Travel Medicine|url=https://academic.oup.com/jtm/article/28/7/taab124/6346388|dato=9. august 2021|forfattere=Ying Liu, Joacim Rocklöv}}</ref>
|-
| [[Polio]] || Gjennom munnen || 5–7
|-
| [[Røde hunder]] || [[luftbåren smitte|Dråper i luft]] || 5–7
|-
| [[Kusma]] || Dråper i luft || 4–7
|-
| [[Kikhoste]] || Dråper i luft || 5.5<ref>{{cite journal |vauthors=Kretzschmar M, Teunis PF, Pebody RG |title=Incidence and reproduction numbers of pertussis: estimates from serological and social contact data in five European countries. |journal=PLOS Med. |volume=7 |issue=6 |pages=e1000291 |year=2010 |pmid=20585374 |doi=10.1371/journal.pmed.1000291 |pmc=2889930}}</ref>
|-
| [[Kopper]] || Dråper i luft || 3.5–6<ref>{{cite journal |last1=Gani |first1=Raymond |last2=Leach |first2=Steve |title=Transmission potential of smallpox in contemporary populations |journal=Nature |dato=Desember 2001 |volume=414 |issue=6865 |pages=748–751 |doi=10.1038/414748a |url=https://www.nature.com/articles/414748a  |language=en |issn=1476-4687}}</ref>
|-
| [[HIV/AIDS]] || Kroppsvæsker || 2–5
|-
| [[SARS]] || Dråper i luft || 2–5<ref>{{cite journal |vauthors=Wallinga J, Teunis P |title=Different epidemic curves for severe acute respiratory syndrome reveal similar impacts of control measures |url=http://171.66.121.65/cgi/content/full/160/6/509 |journal=Am. J. Epidemiol. |volume=160 |issue=6 |pages=509–16 |year=2004 |pmid=15353409 |doi=10.1093/aje/kwh255 |url-status=dead |archiveurl=https://web.archive.org/web/20071006080939/http://171.66.121.65/cgi/content/full/160/6/509 |archivedate=2007-10-06 }} {{Kilde www |url=http://171.66.121.65/cgi/content/full/160/6/509 |tittel=Arkivert kopi |besøksdato=2020-04-08 |arkiv-dato=2007-10-06 |arkiv-url=https://web.archive.org/web/20071006080939/http://171.66.121.65/cgi/content/full/160/6/509 |url-status=yes }}</ref>
|-
| [[Forkjølelse]] || Dråper i luft || 2–3<ref name="Telegraph Ebola">{{cite web |title=Magic formula that will determine whether Ebola is beaten |url=https://www.telegraph.co.uk/news/worldnews/ebola/11213280/Magic-formula-that-will-determine-whether-Ebola-is-beaten.html |website=The Telegraph |publisher=Telegraph.Co.Uk }}</ref> 
|-
| [[Difteri]] || Spytt || 1.7–4.3<ref>{{cite journal |last1=Truelove |first1=Shaun A. |last2=Keegan |first2=Lindsay T. |last3=Moss |first3=William J. |last4=Chaisson |first4=Lelia H. |last5=Macher |first5=Emilie |last6=Azman |first6=Andrew S. |last7=Lessler |first7=Justin |title=Clinical and Epidemiological Aspects of Diphtheria: A Systematic Review and Pooled Analysis |journal=Clinical Infectious Diseases |doi=10.1093/cid/ciz808 |url=https://academic.oup.com/cid/advance-article-abstract/doi/10.1093/cid/ciz808/5551532?redirectedFrom=fulltext|language=en}}</ref>
|-
| [[SARS-CoV-2]]/[[COVID-19]] || Dråper i luft ||1.4–3.9<ref>{{cite journal | vauthors = Li Q, Guan X, Wu P, Wang X, Zhou L, Tong Y, Ren R, Leung KS, Lau EH, Wong JY, Xing X, Xiang N, Wu Y, Li C, Chen Q, Li D, Liu T, Zhao J, Li M, Tu W, Chen C, Jin L, Yang R, Wang Q, Zhou S, Wang R, Liu H, Luo Y, Liu Y, Shao G, Li H, Tao Z, Yang Y, Deng Z, Liu B, Ma Z, Zhang Y, Shi G, Lam TT, Wu JT, Gao GF, Cowling BJ, Yang B, Leung GM, Feng Z | display-authors = 6 | title = Early Transmission Dynamics in Wuhan, China, of Novel Coronavirus-Infected Pneumonia | journal = The New England Journal of Medicine | dato = Januar 2020 | pmid = 31995857 | doi = 10.1056/NEJMoa2001316 }}</ref><ref>{{cite journal |last1=Riou, Julien and Althaus, Christian L. |title=Pattern of early human-to-human transmission of Wuhan 2019 novel coronavirus (2019-nCoV), December 2019 to January 2020 |journal=[[Eurosurveillance]] |dato=2020 |volume=25 |issue=4 | doi = 10.2807/1560-7917.ES.2020.25.4.2000058|pmid=32019669 |pmc= 7001239}}</ref><ref>{{Cite journal |last=Wu |first=Joseph T. |last2=Leung |first2=Kathy |last3=Bushman |first3=Mary |last4=Kishore |first4=Nishant |last5=Niehus |first5=Rene |last6=de Salazar |first6=Pablo M. |last7=Cowling |first7=Benjamin J. |last8=Lipsitch |first8=Marc |last9=Leung |first9=Gabriel M. |dato=19. mars 2020 |title=Estimating clinical severity of COVID-19 from the transmission dynamics in Wuhan, China |url=https://www.nature.com/articles/s41591-020-0822-7 |journal=Nature Medicine |language=en |pages=1–5 |doi=10.1038/s41591-020-0822-7 |issn=1546-170X}}</ref>
|-
| [[Influensa]]<br><small>(Spanskesyken)</small> || Dråper i luft || 1.4–2.8<ref>{{cite journal |author1=Ferguson NM |author2=Cummings DA |author3=Fraser C |author4=Cajka JC |author5=Cooley PC |author6=Burke DS |title=Strategies for mitigating an influenza pandemic |url=https://archive.org/details/sim_nature-uk_2006-07-27_442_7101/page/n148 |journal=Nature |year=2006 |volume=442 |issue=7101 |pages=448-452 |pmid=16642006 |doi=10.1038/nature04795}}</ref>
|-
| [[Influensa]]<br><small>(Svineinfluensa)</small> || Dråper i luft || 1.4–1.6<ref name="Coburn2009">{{cite journal |author1=Coburn BJ |author2=Wagner BG |author3=Blower S |title=Modeling influenza epidemics and pandemics: insights into the future of swine flu (H1N1) |journal=[[BMC Medicine]] |year=2009 |volume=7 |at=Article 30 |pmid=19545404 |doi=10.1186/1741-7015-7-30}}</ref>
|-
| [[Influensa]]<br><small>(Sesonginfluensa)</small> || Dråper i luft || 0.9–2.1<ref name="Coburn2009" />
|-
| [[MERS]] || Dråper i luft || 0.3–0.8<ref>{{cite journal |last1=Kucharski, Adam and Althaus, Christian L. |title=The role of superspreading in Middle East respiratory syndrome coronavirus (MERS-CoV) transmission |journal=Eurosurveillance |dato=2015 |volume=20 |issue=26 |pages=14–8 |doi=10.2807/1560-7917.ES2015.20.25.21167|pmid=26132768 }}</ref>
|}

Det basale reproduksjonstallet er uavhengig av hvor mange som er vaksinert eller immune, mens det effektive reproduksjonstallet ''R''<sub>E</sub> vil bli påvirket av slike tiltak.

Reproduksjonstallet ''R''<sub>0</sub> kan variere og smitte kan f.eks. skje raskere i kaldt klima enn i varmt klima, og spres fortere der folk bor tett enn der det er god plass. ''R''<sub>0</sub> er ikke en biologisk konstant for et bestemt smittestoff eller et mål på sykdommens alvorlighet. ''R''<sub>0</sub> er et tall uten benevning, og angir følgelig ikke smitteutbredelse over tid. ''R''<sub>0</sub> er en funksjon av både menneskelige faktorer samt smittestoffets biologiske egenskaper.<ref name="snl">[https://snl.no/effektivt_reproduksjonstall Effektivt reproduksjonstall] snl.no</ref> Modellene som brukes for å beregne ''R''<sub>0</sub> er avhengige av riktige data. Antall smittede blir lett underestimert fordi noen smittede har få eller ingen symptomer og på grunn av manglende smitteoppsporing eller manglende testkapasitet.<ref name="tidsskriftet">[https://tidsskriftet.no/2020/03/kronikk/covid-19-simuleringsmodeller-ved-epidemier Covid-19: Simuleringsmodeller ved epidemier]</ref>

Reproduksjonstallet er viktig for å modellere hvordan en sykdom kan spre seg, og ut fra modellene kan man si noe om behovet for helsehjelp eller legemidler.