View source for Pandemic

{{short description|Widespread, often global, epidemic of severe infectious disease}}
{{About|pandemics in general|other uses}}
{{cs1 config|name-list-style=vanc}}
{{Use dmy dates|date=July 2023}}
[[File:Field Hospital Visit (49746816753).jpg|thumb|300px|Early in the [[COVID-19 pandemic]], [[convention center]]s (pictured here) were deemed to be ideal sites for [[Field hospital|temporary hospitals]], due to their existing infrastructure (electrical, water, sewage).<ref name=FedNewsNet_20200327/> Hotels and dormitories were also considered appropriate because they can use [[Negative room pressure|negative pressure]] technology.<ref name=FedNewsNet_20200327>{{cite news | vauthors = Serbu J |title=Army Corps sees convention centers as good option to build temporary hospitals |url=https://federalnewsnetwork.com/defense-main/2020/03/army-corps-sees-convention-centers-as-good-option-to-build-temporary-hospitals/ |work=Federal News Network |date=27 March 2020 |archive-url=https://web.archive.org/web/20200414063937/https://federalnewsnetwork.com/defense-main/2020/03/army-corps-sees-convention-centers-as-good-option-to-build-temporary-hospitals/ |archive-date=14 April 2020 |url-status=live }}</ref>]]

A '''pandemic''' ({{IPAc-en|p|æ|n|'|d|ɛ|m|ɪ|k}} {{respell|pan|DEM|ik}}) is an [[epidemic]] of an [[infectious disease]] that has a sudden increase in cases and spreads across a large region, for instance multiple [[continent]]s or worldwide, affecting a substantial number of individuals. Widespread [[endemic (epidemiology)|endemic]] diseases with a stable number of infected individuals such as recurrences of [[seasonal influenza]] are generally excluded as they occur simultaneously in large regions of the globe rather than being spread worldwide.

Throughout [[human history]], there have been a number of pandemics of diseases such as [[smallpox]]. The [[Black Death]], caused by the [[Plague (disease)|Plague]], caused the deaths of up to half of the population of Europe in the 14th century.<ref name="ABC/Reuters">{{cite news|url=http://www.abc.net.au/science/articles/2008/01/29/2149185.htm|title=Black death 'discriminated' between victims (ABC News in Science)|date=29 January 2008|access-date=3 November 2008|url-status=live|archive-url=https://web.archive.org/web/20161220120404/http://www.abc.net.au/science/articles/2008/01/29/2149185.htm|archive-date=20 December 2016|publisher=Australian Broadcasting Corporation}}</ref><ref name="Black Death's Gene Code Cracked">{{cite magazine|url=http://archive.wired.com/medtech/health/news/2001/10/47288|title=Black Death's Gene Code Cracked|magazine=Wired|date=3 October 2001|access-date=12 February 2015|archive-url=https://web.archive.org/web/20150426160438/http://archive.wired.com/medtech/health/news/2001/10/47288|archive-date=26 April 2015|url-status=dead}}</ref><ref name="Health: De-coding the Black Death">{{cite news |url=http://news.bbc.co.uk/2/hi/health/1576875.stm |title=Health: De-coding the Black Death |publisher=BBC |date=3 October 2001 |access-date=3 November 2008 |archive-url=https://web.archive.org/web/20170707042715/http://news.bbc.co.uk/2/hi/health/1576875.stm |archive-date=7 July 2017 |url-status=live }}</ref><ref>{{cite journal | vauthors = DeLeo FR, Hinnebusch BJ | title = A plague upon the phagocytes | journal = Nature Medicine | volume = 11 | issue = 9 | pages = 927–928 | date = September 2005 | pmid = 16145573 | doi = 10.1038/nm0905-927 | s2cid = 31060258 | doi-access = free }}</ref> The term ''pandemic'' had not been used then, but was used for later epidemics, including the 1918 [[Influenza A virus subtype H1N1|H1N1 influenza A]] pandemic—more commonly known as the [[Spanish flu]]—which is the [[Deadliest pandemics in history|deadliest pandemic in history]].<ref>[https://www.cdc.gov/flu/pandemic-resources/1918-pandemics-h1n1.html 1918 Pandemics (H1N1 virus).] [[Centers for Disease Control and Prevention]]. Retrieved 18 April 2020.</ref><ref>{{cite news|title=History's deadliest pandemics, from ancient Rome to modern America|url=https://www.washingtonpost.com/graphics/2020/local/retropolis/coronavirus-deadliest-pandemic/|date=7 April 2020|access-date=11 April 2020| vauthors = Rosenwald MS |newspaper=[[The Washington Post]]|url-status=dead|url-access=subscription|archive-url=https://web.archive.org/web/20200407204000/https://www.washingtonpost.com/graphics/2020/local/retropolis/coronavirus-deadliest-pandemics/|archive-date=7 April 2020}}</ref><ref name="WHO99">{{cite web|url= https://www.who.int/csr/disease/swineflu/laboratory06_08_2010/en/|archive-url= https://web.archive.org/web/20150807183818/http://www.who.int/csr/disease/swineflu/laboratory06_08_2010/en/|url-status= dead|archive-date= 7 August 2015|title=Weekly Virological Update on 05 August 2010 | date=5 August 2010|website=World Health Organization (WHO) |access-date=8 April 2020}}</ref> The most recent pandemics include the [[AIDS pandemic|HIV/AIDS pandemic]],{{efn|Most medical sources, including the WHO, do not refer to HIV/AIDS as a pandemic; those that do refer to it in the past-tense to separate the acute and chronic phases.}}<ref>{{cite journal |display-authors=6 |vauthors=Roychoudhury S, Das A, Sengupta P, Dutta S, Roychoudhury S, Choudhury AP, Ahmed AB, Bhattacharjee S, Slama P |date=December 2020 |title=Viral Pandemics of the Last Four Decades: Pathophysiology, Health Impacts and Perspectives |journal=International Journal of Environmental Research and Public Health |volume=17 |issue=24 |pages=9411 |doi=10.3390/ijerph17249411 |pmc=7765415 |pmid=33333995 |doi-access=free}}</ref> the [[2009 swine flu pandemic]] and the [[COVID-19 pandemic]].<!-- The majority of medical and media sources refer to the COVID-19 and HIV/AIDS pandemic in the past tense. The WHO itself, while it doesn't declare pandemics, does refer to HIV as an epidemic. Please use talk page to discuss changes. --> Almost all these diseases still circulate among humans though their impact now is often far less.

In response to the COVID-19 pandemic, 194 member states of the [[World Health Organization]] began negotiations on an [[International Treaty on Pandemic Prevention, Preparedness and Response]], with a requirement to submit a draft of this treaty to the 77th [[World Health Assembly]] during its 2024 convention.<ref name=":02">{{cite web |date=1 December 2021 |title=World Health Assembly agrees to launch process to develop historic global accord on pandemic prevention, preparedness and response |url=https://www.who.int/news/item/01-12-2021-world-health-assembly-agrees-to-launch-process-to-develop-historic-global-accord-on-pandemic-prevention-preparedness-and-response |access-date=2 December 2021 |website=[[World Health Organization]] }}</ref><ref name=":13">{{cite news | vauthors = Cumming-Bruce N |date=1 December 2021 |title=W.H.O. members agree to begin talks on a global pandemic treaty. |work=The New York Times |url=https://www.nytimes.com/2021/12/01/world/who-pandemic-treaty.html |access-date=2 December 2021 |issn=0362-4331}}</ref> Further, on 6 May 2024, the [[White House]] released an official policy to more safely manage medical research projects involving [[Pathogen|potentially hazardous pathogens]], including [[virus]]es and [[bacteria]], that may pose a risk of a pandemic.<ref name="NYT-20240507">{{cite news |last1=Zimmer |first1=Carl |last2=Mueller |first2=Benjamin |title=U.S. Tightens Rules on Risky Virus Research - A long-awaited new policy broadens the type of regulated viruses, bacteria, fungi and toxins, including those that could threaten crops and livestock. |url=https://www.nytimes.com/2024/05/07/science/covid-lab-leak-biosafety-rules-virus-research.html |date=7 May 2024 |work=[[The New York Times]] |url-status=live |archiveurl=https://archive.today/20240507162105/https://www.nytimes.com/2024/05/07/science/covid-lab-leak-biosafety-rules-virus-research.html |archivedate=7 May 2024 |accessdate=8 May 2024 }}</ref><ref name="WH-20240506">{{cite news |author=[[White House]] |title=United States Government Policy for Oversight of Dual Use Research of Concern and Pathogens with Enhanced Pandemic Potential |url=https://bidenwhitehouse.archives.gov/wp-content/uploads/2024/05/USG-Policy-for-Oversight-of-DURC-and-PEPP.pdf |date=6 May 2024 |work=[[Whitehouse.gov]] |url-status=live |archive-url=https://archive.today/20240508110439/https://www.whitehouse.gov/wp-content/uploads/2024/05/USG-Policy-for-Oversight-of-DURC-and-PEPP.pdf |archive-date=8 May 2024 |access-date=8 May 2024 }}</ref>
{{TOC limit|3}}

== Definition ==
{{multiple image
| align             = right
| direction         = horizontal
| width             = 
| image1            = Doutielt3.jpg
| caption1          = Depiction of the burial of bodies during the [[Black Death]], which killed up to half of Eurasia's population in the 14th century.
| image2            = 1918FluVictimsStLouis.jpg
| caption2          = [[American Red Cross]] workers carry a body during the 1918–20 [[Spanish flu|"Spanish flu" pandemic]].
| total_width       = 450
| alt1              = 
}}
A medical dictionary definition of pandemic is "an [[epidemic]] occurring on a scale that crosses international boundaries, usually affecting people on a worldwide scale".<ref name=Porta2008>{{cite book| veditors = Porta M |title=Dictionary of Epidemiology|url=https://books.google.com/books?id=3Dr8dyuzvTkC&pg=PA179|access-date=14 September 2012|year=2008|publisher=Oxford University Press|isbn=978-0-19-531449-6|page=179}}</ref> A disease or condition is not a pandemic merely because it is widespread or kills many people; it must also be infectious. For instance, [[cancer]] is responsible for many deaths but is not considered a pandemic because the disease is not [[Infection#Contagiousness|contagious]]—i.e. easily transmissible—and not even simply [[Infection|infectious]].<ref>{{cite book | vauthors = Dumar AM |title=Swine Flu: What You Need to Know |date=2009 |publisher=Wildside Press LLC |isbn=978-1434458322 |page=7}}</ref> This definition differs from colloquial usage in that it encompasses outbreaks of relatively mild diseases.<ref>{{cite journal | vauthors = Morens D, Folkers G, Fauci A |date=1 October 2009 |title=What Is a Pandemic? |url=https://academic.oup.com/jid/article/200/7/1018/903237 |access-date=7 June 2023 |journal=The Journal of Infectious Diseases |volume=200 |issue=7 |pages=1018–1021 |doi=10.1086/644537 |pmid=19712039 |url-access=subscription }}</ref><ref>{{cite journal | vauthors = Doshi P | title = The elusive definition of pandemic influenza | journal = Bulletin of the World Health Organization | volume = 89 | issue = 7 | pages = 532–538 | date = July 2011 | pmid = 21734768 | pmc = 3127275 | doi = 10.2471/BLT.11.086173 }}</ref>

The [[World Health Organization]] (WHO) has a category of [[Public health emergency of international concern|Public Health Emergency of International Concern]], defined as "an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response".<ref>{{cite web |date=19 December 2019 |title=Emergencies: International health regulations and emergency committees |url=https://www.who.int/news-room/questions-and-answers/item/emergencies-international-health-regulations-and-emergency-committees |access-date=7 June 2023 |website=World Health Organization }}</ref> There is a rigorous process underlying this categorization and a clearly defined trajectory of responses.<ref>{{cite web | vauthors = Ross E |date=20 October 2022 |title=What is the difference between a pandemic and a PHEIC? (Video) |url=https://www.chathamhouse.org/2022/10/what-difference-between-pandemic-and-pheic |access-date=7 June 2023 |website=Chatham House, The Royal Institute of International Affairs}}</ref>

A WHO-sponsored international body, tasked with preparing an [[International Treaty on Pandemic Prevention, Preparedness and Response|international agreement on pandemic prevention, preparedness and response]] has defined a pandemic as "the global spread of a pathogen or variant that infects human populations with limited or no immunity through sustained and high transmissibility from person to person, overwhelming health systems with severe morbidity and high mortality, and causing social and economic disruptions, all of which require effective national and global collaboration and coordination for its control".<ref>{{cite web |date=1 February 2023 |title=Zero draft of the WHO convention, agreement or other international instrument on pandemic prevention, preparedness and response ("WHO CA+") |url=https://apps.who.int/gb/inb/pdf_files/inb4/A_INB4_3-en.pdf |access-date=7 June 2023 |website=World Health Organization – Intergovernmental Negotiating Body}}</ref>

The word comes from the [[Ancient Greek|Greek]] {{Lang|grc|παν-}} {{Lang|grc-latn|pan-}} meaning {{Gloss|all, every}}, and {{Lang|grc|δῆμος}} {{Lang|grc-latn|demos}} {{Gloss|people}}.

=== Parameters ===
A common early characteristic of a pandemic is a rapid, sometimes [[Exponential growth|exponential]], growth in the number of infections, coupled with a widening geographical spread.<ref>{{Cite journal |last1=Foster |first1=Grant |last2=Elderd |first2=Bret D |last3=Richards |first3=Robert L |last4=Dallas |first4=Tad |date=2022-09-01 |editor-last=Wilson |editor-first=Ian |title=Estimating R 0 from early exponential growth: parallels between 1918 influenza and 2020 SARS-CoV-2 pandemics |url=https://academic.oup.com/pnasnexus/article/doi/10.1093/pnasnexus/pgac194/6702748 |journal=PNAS Nexus |language=en |volume=1 |issue=4 |pages=pgac194 |doi=10.1093/pnasnexus/pgac194 |issn=2752-6542 |pmc=9802102 |pmid=36714850}}</ref>

[[World Health Organization|WHO]] utilises different criteria to declare a [[Public health emergency of international concern|Public Health Emergency of International Concern]] (PHEIC), its nearest equivalent to the term ''pandemic.''<ref>{{Cite web |last=Ross |first=Emma |date=20 Oct 2022 |title=What is the difference between a pandemic and a PHEIC (Video explainer) |url=https://www.chathamhouse.org/2022/10/what-difference-between-pandemic-and-pheic |access-date=25 August 2023 |website=Chatham House, The Royal Institute of International Affairs |quote=There's a whole infrastructure and official process around designating something a PHEIC and designating that an outbreak is no longer a PHEIC. There's none of that when it comes to calling an outbreak pandemic.}}</ref> The potential consequences of an incident are considered, rather than its current status.<ref>{{Cite journal |last1=Wilder-Smith |first1=Annelies |last2=Osman |first2=Sarah |date=2020-12-23 |title=Public health emergencies of international concern: a historic overview |journal=Journal of Travel Medicine |language=en |volume=27 |issue=8 |doi=10.1093/jtm/taaa227 |issn=1195-1982 |pmc=7798963 |pmid=33284964}}</ref> For example, [[polio]] was [[Polio eradication#2011–2015|declared a PHEIC]] in 2014 even though only 482 cases were reported globally in the previous year;<ref>{{Cite web |title=GHO {{!}} By category {{!}} Poliomyelitis - Reported cases by country |url=https://apps.who.int/gho/data/node.main.WHS3_49?lang=en |access-date=2023-08-25 |website=WHO}}</ref> this was justified by concerns that polio might break out of its endemic areas and again become a significant health threat globally.<ref>{{Cite web |date=5 May 2014 |title=WHO statement on the meeting of the International Health Regulations Emergency Committee concerning the international spread of wild poliovirus |url=https://www.who.int/news/item/05-05-2014-who-statement-on-the-meeting-of-the-international-health-regulations-emergency-committee-concerning-the-international-spread-of-wild-poliovirus |access-date=25 August 2023 |website=World Health Organization |language=en}}</ref> The PHEIC status of polio is reviewed regularly and is ongoing, despite the small number of cases annually.{{Efn|As of August 2023}}<ref>{{Cite web |title=Statement of the Thirty-sixth Meeting of the Polio IHR Emergency Committee |url=https://www.who.int/news/item/25-08-2023-statement-of-the-thirty-sixth-meeting-of-the-polio-ihr-emergency-committee |access-date=2023-08-25 |website=www.who.int |language=en}}</ref>

The end of a pandemic is more difficult to delineate. Generally, past epidemics and pandemics have faded out as the diseases become accepted into people's daily lives and routines, becoming [[Endemic (epidemiology)|endemic]].<ref>{{Cite journal |last1=Charters |first1=Erica |last2=Heitman |first2=Kristin |date=February 2021 |title=How epidemics end |journal=Centaurus |language=en |volume=63 |issue=1 |pages=210–224 |doi=10.1111/1600-0498.12370 |issn=0008-8994 |pmc=8014506 |pmid=33821019}}</ref> The transition from pandemic to endemic may be defined based on:

* a high proportion of the global population having immunity (through either natural infection or vaccination)
* fewer deaths
* health systems step down from emergency status
* perceived personal risk is lessened
* restrictive measures such as [[Travel during the COVID-19 pandemic|travel restrictions]] removed
* less coverage in public media.<ref name=":0">{{Cite journal |last=Ioannidis |first=John P. A. |date=June 2022 |title=The end of the COVID-19 pandemic |journal=European Journal of Clinical Investigation |language=en |volume=52 |issue=6 |pages=e13782 |doi=10.1111/eci.13782 |issn=0014-2972 |pmc=9111437 |pmid=35342941}}</ref><ref>{{Cite news |last=Steenhuysen |first=Julie |date=2021-11-17 |title=Fauci says boosters for all key to U.S. reaching COVID-19 endemic level |language=en |work=Reuters |url=https://www.reuters.com/world/us/fauci-says-us-can-reach-covid-endemic-level-rather-than-pandemic-next-year-2021-11-16/ |access-date=2023-08-22}}</ref>

An endemic disease is always present in a population, but at a relatively low and predictable level. There may be periodic spikes of infections or seasonality, (e.g. [[influenza]]) but generally the burden on health systems is manageable.<ref name=":0" />

== Prevention and preparedness ==
{{Main|Pandemic prevention}}
[[File:Pandemic_prevention_infographic.png|thumb|Infographic illustrating the benefits of a treaty for pandemic prevention]]
Pandemic '''prevention''' comprises activities such as anticipatory research and development of therapies and vaccines, as well as monitoring for pathogens and disease outbreaks which may have pandemic potential.<ref name="PP_Why">{{Cite web | vauthors = Williams N |date=6 July 2022 |title=What is Pandemic Preparedness and Why is it Important? |url=https://www.news-medical.net/health/What-is-Pandemic-Preparedness-and-Why-is-it-Important.aspx |access-date=20 August 2023 |website=News Medical Network |language=en}}</ref> [[Routine vaccinations|Routine vaccination]] programs are a type of prevention strategy, holding back diseases such as [[influenza]] and [[polio]] which have caused pandemics in the past, and could do so again if not controlled.<ref>{{Cite web |date=15 September 2022 |title=14 Diseases You Almost Forgot About (Thanks to Vaccines) |url=https://www.cdc.gov/vaccines/parents/diseases/forgot-14-diseases.html |access-date=21 August 2023 |website=Centers for Disease Control and Prevention |language=en-us}}</ref> Prevention overlaps with '''preparedness''' which aims to curtail an outbreak and prevent it getting out of control - it involves strategic planning, data collection and modelling to measure the spread, stockpiling of therapies, vaccines, and medical equipment, as well as public health awareness campaigning.<ref>{{Cite web | vauthors = Campbell K |date=15 November 2022 |title=3 Steps to Detect and Stop Disease Outbreaks before They Become Pandemics |url=https://www.scientificamerican.com/article/3-steps-to-detect-and-stop-disease-outbreaks-before-they-become-pandemics/ |access-date=21 August 2023 |website=Scientific American |language=en}}</ref> By definition, a pandemic involves many countries so international cooperation, data sharing, and collaboration are essential; as is universal access to tests and therapies.<ref name="PP_Why" />

'''Collaboration''' – In response to the COVID-19 pandemic, WHO established a Pandemic Hub in September 2021 in Berlin, aiming to address weaknesses around the world in how countries detect, monitor and manage public health threats. The Hub's initiatives include using artificial intelligence to analyse more than 35,000 data feeds for indications of emerging health threats, as well as improving facilities and coordination between academic institutions and WHO member countries.<ref>{{cite journal | vauthors = Morgan O, Pebody R | title = The WHO Hub for Pandemic and Epidemic Intelligence; supporting better preparedness for future health emergencies | journal = Euro Surveillance | volume = 27 | issue = 20 | pages = 2200385 | date = May 2022 | pmid = 35593162 | pmc = 9121660 | doi = 10.2807/1560-7917.ES.2022.27.20.2200385 }}</ref>

'''Detection''' – In May 2023, WHO launched the International Pathogen Surveillance Network (IPSN) (hosted by the Pandemic Hub) aiming to detect and respond to disease threats before they become epidemics and pandemics, and to optimize routine disease surveillance. The network provides a platform to connect countries, improving systems for collecting and analysing samples of potentially harmful [[pathogen]]s.<ref>{{Cite web |date=20 May 2023 |title=WHO launches global network to detect and prevent infectious disease threats |url=https://www.who.int/news/item/20-05-2023-who-launches-global-network-to--detect-and-prevent-infectious-disease-threats |access-date=2023-08-17 |website=World Health Organization |language=en}}</ref> [[Wastewater-based epidemiology|Wastewater surveillance]] can for example provide early warnings by detecting pathogens in sewage.<ref>{{Cite web |date=14 February 2024 |title=How sewers are helping us to monitor disease outbreaks |url=https://www.bbc.com/future/article/20240213-how-sewers-are-helping-us-to-monitor-disease-outbreaks |access-date=2025-01-05 |website=BBC |language=en-GB}}</ref>

'''Therapies and vaccines''' – The [[Coalition for Epidemic Preparedness Innovations]] (CEPI) is developing a program as part of their 2022–2026 pandemic plan to condense new vaccine development timelines to 100 days, less than a third of the time it took to develop a COVID-19 vaccine.<ref>{{cite journal |vauthors=Gouglas D, Christodoulou M, Hatchett R |date=March 2023 |title=The 100 Days Mission—2022 Global Pandemic Preparedness Summit |journal=Emerg Infect Dis |volume=29 |issue=3 |page=e221142 |doi=10.3201/eid2903.221142 |pmc=9973700 |pmid=}}</ref><ref>{{cite journal |vauthors=Saville M, Cramer JP, Downham M, Hacker A, Lurie N, Van der Veken L, Whelan M, Hatchett R |date=14 July 2022 |title=Delivering Pandemic Vaccines in 100 Days - What Will It Take? |journal=N Engl J Med |volume=387 |issue=2 |page=e3 |doi=10.1056/NEJMp2202669 |pmc= |pmid=35249271}}</ref> In the US, the [[National Institute of Allergy and Infectious Diseases]] (NIAID) has developed a Pandemic Preparedness Plan which focuses on identifying viruses of concern and developing diagnostics and therapies (including prototype vaccines) to combat them.<ref>{{Cite web |date=December 2021 |title=Pandemic Preparedness |url=https://www.niaid.nih.gov/research/pandemic-preparedness |access-date=21 August 2023 |website=NIH: National Institute of Allergy and Infectious Diseases |language=en}}</ref><ref>{{Cite web |date=December 2021 |title=NIAID Pandemic Preparedness Plan (pdf) |url=https://www.niaid.nih.gov/sites/default/files/pandemic-preparedness-plan.pdf |access-date=21 August 2023 |website=National Institute of Allergy and Infectious Diseases}}</ref>

'''Modeling''' is important to inform policy decisions. It helps to predict the burden of disease on healthcare facilities, the effectiveness of control measures, projected geographical spread, and timing and extent of future pandemic waves.<ref>{{Cite web |date=1 December 2022 |title=Technical report on the COVID-19 pandemic in the UK - Chapter 5: modelling |url=https://www.gov.uk/government/publications/technical-report-on-the-covid-19-pandemic-in-the-uk/chapter-5-modelling |access-date=21 August 2023 |website=Department of Health & Social Care |language=en}}</ref>

'''Public awareness''' involves disseminating reliable information, ensuring consistency in message, transparency, and steps to discredit [[misinformation]].<ref>{{Cite report | vauthors = Bellantoni A, Badr K, Alfonsi C |url=https://www.oecd-ilibrary.org/governance/transparency-communication-and-trust_bef7ad6e-en |title=Transparency, communication and trust: The role of public communication in responding to the wave of disinformation about the new Coronavirus |series=OECD Policy Responses to Coronavirus (COVID-19) |date=3 July 2020 |publisher=Organisation for Economic Co-operation and Development |doi=10.1787/bef7ad6e-en |language=en |access-date=21 August 2023|doi-access=free |url-access=subscription }}</ref>

'''Air quality''' – Enhanced indoor [[Ventilation (architecture)|ventilation]] and [[air filtration]] systems are also effective at reducing [[Airborne transmission|transmission of airborne pathogens]], while providing additional health benefits beyond pandemic control.<ref>{{Cite web |date=2022-08-24 |title=The two big pandemic investments we still need to make |url=https://www.vox.com/science-and-health/23316936/covid-19-pandemic-spending-cost-effective-vaccines-ventilation-filtration-air-quality |access-date=2025-01-05 |website=Vox |language=en-US}}</ref>

'''Stockpiling''' involves maintaining strategic [[Stockpiling antiviral medications for pandemic influenza|stockpiles]] of emergency supplies such as [[personal protective equipment]], drugs and vaccines, and equipment such as respirators. Many of these items have limited [[shelf life]], so they require [[stock rotation]] even though they may be rarely used.<ref>{{Cite web |date=28 July 2022 | vauthors = Lovelace Jr B, Bauer T, Torres J |title=A rare look inside the Strategic National Stockpile — and how it went wrong at the start of the pandemic |url=https://www.nbcnews.com/health/health-news/rare-look-strategic-national-stockpile-went-wrong-start-pandemic-rcna32603 |access-date=21 August 2023 |website=NBC News |language=en}}</ref>

=== Ethical and political issues ===
The COVID-19 pandemic highlighted a number of ethical and political issues which must be considered during a pandemic. These included decisions about who should be prioritised for treatment while resources are scarce; whether or not to make vaccination compulsory; the timing and extent of constraints on individual liberty, how to sanction individuals who do not comply with emergency regulations, and the extent of international collaboration and resource sharing.<ref>{{Cite web |date=2 May 2023 |title=Are we ethically prepared for Disease X? |url=https://www.ox.ac.uk/news/2023-05-02-are-we-ethically-prepared-disease-x |access-date=2024-01-15 |website=University of Oxford |language=en}}</ref><ref>{{Cite book |last1=Savulescu |first1=Julian |title=Pandemic Ethics |last2=Wilkinson |first2=Dominic |date=1 May 2023 |publisher=Oxford University Press |isbn=9780192871688 |location=Oxford, UK}}</ref>

== Pandemic management strategies ==
{{See also|Mathematical modelling of infectious disease}}
[[File:Social distancing queueing for the supermarket J. Sainsbury's north London Coronavirus Covid 19 pandemic - 30 March 2020.jpg|thumb|Social distancing in public]]
{{multiple image
| align             = right
| direction         = horizontal
| total_width       = 450
| image1            = 20200410 Flatten the curve, raise the line - pandemic (English).gif
| caption1          = Goals of mitigation include delaying and reducing peak burden on healthcare (''[[flattening the curve]]'') and lessening overall cases and health impact.<ref name=Lancet2020Flatten/><ref name="community mitigation">{{cite journal |url=https://stacks.cdc.gov/view/cdc/45220 |title=Community Mitigation Guidelines to Prevent Pandemic Influenza—United States, 2017 |journal=Recommendations and Reports |volume= 66 |number= 1 |date=12 April 2017|publisher=Centers for Disease Control and Prevention }}</ref> Also, increasing healthcare capacity (''[[raising the line]]'', as by increasing bed count, personnel, and equipment) helps to meet increased demand.<ref name=Vox_20200407>{{cite news | vauthors = Barclay E, Scott D, Animashaun A |title=The US doesn't just need to flatten the curve. It needs to "raise the line." |url=https://www.vox.com/2020/4/7/21201260/coronavirus-usa-chart-mask-shortage-ventilators-flatten-the-curve |work=Vox |date=7 April 2020 |archive-url=https://web.archive.org/web/20200407155950/https://www.vox.com/2020/4/7/21201260/coronavirus-usa-chart-mask-shortage-ventilators-flatten-the-curve |archive-date=7 April 2020 |url-status=live }}</ref><ref name="ACAIM-WACEM COVID-19 Consensus Paper">{{cite journal | vauthors = Stawicki SP, Jeanmonod R, Miller AC, Paladino L, Gaieski DF, Yaffee AQ, De Wulf A, Grover J, Papadimos TJ, Bloem C, Galwankar SC, Chauhan V, Firstenberg MS, Di Somma S, Jeanmonod D, Garg SM, Tucci V, Anderson HL, Fatimah L, Worlton TJ, Dubhashi SP, Glaze KS, Sinha S, Opara IN, Yellapu V, Kelkar D, El-Menyar A, Krishnan V, Venkataramanaiah S, Leyfman Y, Saoud Al Thani HA, Wb Nanayakkara P, Nanda S, Cioè-Peña E, Sardesai I, Chandra S, Munasinghe A, Dutta V, Dal Ponte ST, Izurieta R, Asensio JA, Garg M | display-authors = 6 | title = The 2019–2020 Novel Coronavirus (Severe Acute Respiratory Syndrome Coronavirus 2) Pandemic: A Joint American College of Academic International Medicine-World Academic Council of Emergency Medicine Multidisciplinary COVID-19 Working Group Consensus Paper | journal = Journal of Global Infectious Diseases | volume = 12 | issue = 2 | pages = 47–93 | year = 2020 | pmid = 32773996 | pmc = 7384689 | doi = 10.4103/jgid.jgid_86_20 | s2cid = 218754925 | doi-access = free }}</ref>
| image2            = 20200409 Pandemic resurgence - effect of inadequate mitigation.gif
| caption2          = Mitigation attempts that are inadequate in strictness or duration—such as premature relaxation of physical distancing rules or stay-at-home orders—can allow a resurgence after the initial surge and mitigation.<ref name=Lancet2020FlattenNoQuote>{{cite journal | vauthors = Anderson RM, Heesterbeek H, Klinkenberg D, Hollingsworth TD | title = How will country-based mitigation measures influence the course of the COVID-19 epidemic? | journal = Lancet | volume = 395 | issue = 10228 | pages = 931–934 | date = March 2020 | pmid = 32164834 | pmc = 7158572 | doi = 10.1016/S0140-6736(20)30567-5 }}</ref>
}}

{{multiple image
| align             = right
| direction         = horizontal
| total_width       = 450
| image3            = 20200609 Effect of pandemic containment measures.gif
| caption3          = Without pandemic containment measures—such as social distancing, vaccination, and use of face masks—pathogens can spread exponentially.<ref name=Science_20200515>{{cite journal | vauthors = Maier BF, Brockmann D | title = Effective containment explains subexponential growth in recent confirmed COVID-19 cases in China | journal = Science | volume = 368 | issue = 6492 | pages = 742–746 | date = May 2020 | pmid = 32269067 | pmc = 7164388 | doi = 10.1126/science.abb4557 | arxiv = 2002.07572 | bibcode = 2020Sci...368..742M }} ("...initial exponential growth expected for an unconstrained outbreak.")</ref> This graphic shows how early adoption of containment measures tends to protect wider swaths of the population.
| image4            = 19180927 Gauze Mask to Halt Spread of Plague (Spanish flu) - The Washington Times.jpg
| caption4          = The Red Cross recommended two-layer gauze masks to contain the Spanish flu (1918).<ref name=WashTimes_19180927>{{cite news |title=Gauze Mask to Halt Spread of Plague |url=https://newspaperarchive.com/washington-times-sep-27-1918-p-3/ |work=The Washington Times |date=27 September 1918 |page=3}}</ref>
}}

The basic strategies in the control of an outbreak are '''containment''' and '''mitigation'''. Containment may be undertaken in the early stages of the outbreak, including [[contact tracing]] and isolating infected individuals to stop the disease from spreading to the rest of the population, other public health interventions on infection control, and therapeutic countermeasures such as [[vaccination]]s which may be effective if available.<ref>{{cite book |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK54163/ |title=Ethical and Legal Considerations in Mitigating Pandemic Disease: Workshop Summary |chapter=3. Strategies for Disease Containment |year=2007 |publisher=National Academies Press (US) }}</ref> When it becomes apparent that it is no longer possible to contain the spread of the disease, management will then move on to the mitigation stage, in which measures are taken to slow the spread of the disease and mitigate its effects on society and the healthcare system. In reality, containment and mitigation measures may be undertaken simultaneously.<ref>{{cite magazine |url=https://www.newyorker.com/news/news-desk/what-it-means-to-contain-and-mitigate-the-coronavirus |title=What It Means to Contain and Mitigate the Coronavirus| vauthors = Baird RP |date=11 March 2020 |magazine=The New Yorker}}</ref>

A key part of managing an infectious disease outbreak is trying to decrease the epidemic peak, known as "[[flattening the curve]]".<ref name="Lancet2020Flatten" /><ref name="ACAIM-WACEM COVID-19 Consensus Paper" /> This helps decrease the risk of health services being overwhelmed and provides more time for a vaccine and treatment to be developed.<ref name="Lancet2020Flatten">{{cite journal | vauthors = Anderson RM, Heesterbeek H, Klinkenberg D, Hollingsworth TD | title = How will country-based mitigation measures influence the course of the COVID-19 epidemic? | journal = Lancet | volume = 395 | issue = 10228 | pages = 931–934 | date = March 2020 | pmid = 32164834 | pmc = 7158572 | doi = 10.1016/S0140-6736(20)30567-5 | quote = A key issue for epidemiologists is helping policymakers decide the main objectives of mitigation—e.g., minimizing morbidity and associated mortality, avoiding an epidemic peak that overwhelms health-care services, keeping the effects on the economy within manageable levels, and flattening the epidemic curve to wait for vaccine development and manufacture on the scale and antiviral drug therapies. | doi-access = free }}</ref><ref name="ACAIM-WACEM COVID-19 Consensus Paper" /> A broad group of [[Non-pharmaceutical intervention (epidemiology)|non-pharmaceutical interventions]] may be taken to manage the outbreak.<ref name="ACAIM-WACEM COVID-19 Consensus Paper" /> In a flu pandemic, these actions may include personal preventive measures such as hand hygiene, wearing face-masks, and self-quarantine; community measures aimed at [[social distancing]] such as closing schools and canceling mass gatherings; community engagement to encourage acceptance and participation in such interventions; and environmental measures such as cleaning of surfaces.<ref name="community mitigation" />

Another strategy, '''suppression''', requires more extreme long-term non-pharmaceutical interventions to reverse the pandemic by reducing the [[basic reproduction number]] to less than{{nbsp}}1. The suppression strategy, which includes stringent population-wide social distancing, home isolation of cases, and household quarantine, was undertaken by [[China]] during the [[COVID-19 pandemic]] where entire cities were placed under lockdown; such a strategy may carry with it considerable social and economic costs.<ref name="ImpCollege16mar2020">{{cite news |title=Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand |date=16 March 2020 |work=[[Imperial College]] COVID-19 Response Team |url=https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Imperial-College-COVID19-NPI-modelling-16-03-2020.pdf}}</ref>

== Frameworks for influenza pandemics ==
{{Main|Influenza pandemic}}

=== WHO system ===
For a novel [[influenza virus]], WHO previously applied a six-stage classification to delineate the process by which the virus moves from the first few infections in humans through to a pandemic. Starting with phase 1 (infections identified in animals only), it moves through phases of increasing infection and spread to phase 6 (pandemic).<ref>{{Cite book |url=https://apps.who.int/iris/bitstream/handle/10665/44123/9789241547680_eng.pdf |title=Pandemic influenza preparedness and response: a WHO guidance document |date=2009 | publisher = World Health Organization |isbn=978-92-4-154768-0 |pages=24–27 |access-date=17 August 2023}}</ref> In February 2020, a WHO spokesperson clarified that the system is no longer in use.<ref name="ReutersWHOnoLongerUsesPandemic">{{cite news |date=24 February 2020 |title=WHO says it no longer uses 'pandemic' category, but virus still emergency |publisher=Reuters |url=https://www.reuters.com/article/uk-china-health-who-idUKKCN20I0PD |url-status=live |archive-url=https://web.archive.org/web/20200318024718/https://www.reuters.com/article/uk-china-health-who-idUKKCN20I0PD |archive-date=18 March 2020 |quote=For the sake of clarification, WHO does not use the old system of 6 phases—that ranged from phase 1 (no reports of animal influenza causing human infections) to phase 6 (a pandemic)—that some people may be familiar with from H1N1 in 2009.}}</ref>

=== CDC Frameworks ===
[[File:Pandemic Intervals Framework Influenza Intervals.jpg|thumb|Influenza intervals in the CDC's Pandemic Intervals Framework]]

In 2014, the United States [[Centers for Disease Control and Prevention]] (CDC) introduced a framework for characterising the progress of an influenza pandemic titled the ''Pandemic Intervals Framework''.<ref name="Holloway2014">{{cite journal |vauthors=Holloway R, Rasmussen SA, Zaza S, Cox NJ, Jernigan DB |date=September 2014 |title=Updated preparedness and response framework for influenza pandemics |url=https://www.cdc.gov/flu/pandemic-resources/pdf/mmwr-rr6306.pdf |journal=MMWR. Recommendations and Reports |publisher=Center for Surveillance, Epidemiology, and Laboratory Services, Centers for Disease Control and Prevention |volume=63 |issue=RR-06 |pages=1–18 |pmid=25254666 |access-date=10 May 2020}}</ref> The six intervals of the framework are as follows:

* investigation of cases of novel influenza, 
* recognition of increased potential for ongoing transmission, 
* initiation of a pandemic wave, 
* acceleration of a pandemic wave, 
* deceleration of a pandemic wave, and 
* preparation for future pandemic waves.

At the same time, the CDC adopted the [[Pandemic Severity Assessment Framework]] (PSAF) to assess the severity of influenza pandemics.<ref name="Holloway2014" /> The PSAF rates the severity of an influenza outbreak on two dimensions: clinical severity of illness in infected persons; and the transmissibility of the infection in the population.<ref name="Reed2013">{{cite journal | vauthors = Reed C, Biggerstaff M, Finelli L, Koonin LM, Beauvais D, Uzicanin A, Plummer A, Bresee J, Redd SC, Jernigan DB | display-authors = 6 | title = Novel framework for assessing epidemiologic effects of influenza epidemics and pandemics | journal = Emerging Infectious Diseases | volume = 19 | issue = 1 | pages = 85–91 | date = January 2013 | pmid = 23260039 | pmc = 3557974 | doi = 10.3201/eid1901.120124 }}</ref> This tool was not applied during the COVID-19 pandemic.<ref>{{cite journal | vauthors = Bhatia R, Sledge I, Baral S | title = Missing science: A scoping study of COVID-19 epidemiological data in the United States | journal = PLOS ONE | volume = 17 | issue = 10 | pages = e0248793 | date = 2022-10-12 | pmid = 36223335 | pmc = 9555641 | doi = 10.1371/journal.pone.0248793 | doi-access = free | bibcode = 2022PLoSO..1748793B }}</ref>

== Notable pandemics and outbreaks ==
{{See also|List of epidemics|Columbian Exchange|Globalization and disease}}

=== Recent outbreaks ===
<!-- Please restrict this to the last 50 years -->

==== COVID-19 ====
{{Main|COVID-19|COVID-19 pandemic}}
[[File:Total-confirmed-cases-of-covid-19-per-million-people.png|thumb|Total confirmed cases of COVID-19 per million people<ref>{{cite web |title=Total confirmed cases of COVID-19 per million people |url=https://ourworldindata.org/grapher/total-confirmed-cases-of-covid-19-per-million-people |website=Our World in Data |access-date=10 April 2020 |archive-url=https://web.archive.org/web/20200319163452/https://ourworldindata.org/grapher/total-confirmed-cases-of-covid-19-per-million-people |archive-date=19 March 2020 |url-status=live }}</ref>]]
[[SARS-CoV-2]], a new strain of [[coronavirus]], was first detected in the city of [[Wuhan|Wuhan, Hubei Province]], China, in December 2019.<ref>{{cite web |date=31 December 2019 |title=WHO Statement Regarding Cluster of Pneumonia Cases in Wuhan, China |url=https://www.who.int/china/news/detail/09-01-2020-who-statement-regarding-cluster-of-pneumonia-cases-in-wuhan-china |access-date=12 March 2020 |publisher=WHO}}</ref> The outbreak was characterized as a [[Public health emergency of international concern|Public Health Emergency of International Concern]] (PHEIC) between January 2020 and May 2023 by WHO.<ref>{{cite web |date=11 March 2020 |title=WHO Director-General's opening remarks at the media briefing on COVID-19—11 March 2020 |url=https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---11-march-2020 |access-date=12 March 2020 |publisher=WHO}}</ref><ref>{{cite web |title=WHO – Statement on the fifteenth meeting of the IHR (2005) Emergency Committee on the COVID-19 pandemic |url=https://www.who.int/news/item/05-05-2023-statement-on-the-fifteenth-meeting-of-the-international-health-regulations-(2005)-emergency-committee-regarding-the-coronavirus-disease-(covid-19)-pandemic |access-date=10 May 2023 |publisher=World Health Organization}}</ref> The number of people infected with COVID-19 has reached more than 767 million worldwide, with a death toll of 6.9 million.{{Efn|Statistics as of August 2023}}<ref>{{cite web |date=19 June 2023 |title=WHO Coronavirus (COVID-19) Dashboard |url=https://covid19.who.int/ |access-date=19 June 2023 |website=World Health Organization}}</ref> It is considered likely that the virus will eventually become endemic and, like the common cold, cause less severe disease for most people.<ref>{{cite journal | vauthors = Harrison CM, Doster JM, Landwehr EH, Kumar NP, White EJ, Beachboard DC, Stobart CC | title = Evaluating the Virology and Evolution of Seasonal Human Coronaviruses Associated with the Common Cold in the COVID-19 Era | journal = Microorganisms | volume = 11 | issue = 2 | pages = 445 | date = February 2023 | pmid = 36838410 | pmc = 9961755 | doi = 10.3390/microorganisms11020445 | quote = After evaluating the biology, pathogenesis, and emergence of the human coronaviruses that cause the common cold, we can anticipate that with increased vaccine immunity to SARS-CoV-2, it will become a seasonal, endemic coronavirus that causes less severe disease in most individuals. Much like the common cold CoVs, the potential for severe disease will likely be present in those who lack a protective immune response or are immunocompromised. | doi-access = free }}</ref>

==== HIV/AIDS ====
{{Main|HIV/AIDS|Epidemiology of HIV/AIDS}}
[[File:World map of HIV prevalence, 2023.png|thumb|A world map illustrating the proportion of population infected with HIV in 2023]]
[[HIV/AIDS]] was first identified as a disease in 1981, and is an ongoing worldwide [[public health]] issue.<ref name=":2">{{Cite web |date=2 August 2023 |title=HIV/AIDS Factsheet |url=https://www.who.int/news-room/fact-sheets/detail/hiv-aids |access-date=2 August 2023 |website=World Health Organization |language=en}}</ref><ref>{{Cite web |title=Why the HIV epidemic is not over |url=https://www.who.int/news-room/spotlight/why-the-hiv-epidemic-is-not-over |access-date=2022-03-11 |website=www.who.int |language=en}}</ref> Since then, HIV/AIDS has killed an estimated 40 million people with a further 630,000 deaths annually; 39 million people are currently living with [[HIV]] infection.{{Efn|Statistics as at the end of 2022}}<ref name=":2" /> HIV has a [[zoonotic]] origin, having originated in nonhuman [[primate]]s in [[Central Africa]] and transferred to humans in the early 20th century.<ref name="Orgin2011">{{cite journal |vauthors=Sharp PM, Hahn BH |date=September 2011 |title=Origins of HIV and the AIDS pandemic |journal=Cold Spring Harbor Perspectives in Medicine |volume=1 |issue=1 |pages=a006841 |doi=10.1101/cshperspect.a006841 |pmc=3234451 |pmid=22229120}}</ref> The most frequent mode of transmission of HIV is through sexual contact with an infected person. There may be a short period of mild, nonspecific symptoms followed by an asymptomatic (but nevertheless infectious) stage called [[clinical latency]] – without treatment, this stage can last between 3 and 20 years. The only way to detect infection is by means of a HIV test.<ref name="AIDS2010GOV">{{cite web |date=2017-05-15 |title=What Are HIV and AIDS? |url=https://www.hiv.gov/hiv-basics/overview/about-hiv-and-aids/what-are-hiv-and-aids/ |access-date=2 August 2023 |website=HIV.gov |publisher=U.S. Department of Health & Human Services |language=en}}</ref> There is no vaccine to prevent HIV infection, but the disease can be held in check by means of [[Management of HIV/AIDS|antiretroviral therapy]].<ref>{{Cite web |date=16 August 2021 |title=HIV Treatment: The Basics {{!}} NIH |url=https://hivinfo.nih.gov/understanding-hiv/fact-sheets/hiv-treatment-basics |access-date=2 August 2023 |website=hivinfo.nih.gov (a service of the U.S. Department of Health and Human Services) |language=en}}</ref>

=== Pandemics in history ===
{{See also|List of epidemics and pandemics}}Historical accounts of epidemics are often vague or contradictory in describing how victims were affected. A rash accompanied by a fever might be smallpox, measles, scarlet fever, or [[varicella]], and it is possible that epidemics overlapped, with multiple infections striking the same population at once. It is often impossible to know the exact causes of mortality, although [[ancient DNA]] studies can sometimes detect residues of certain pathogens.<ref name="pest">{{cite book |url=https://books.google.com/books?id=YiHHnV08ebkC&pg=PA62 |title=A Pest in the Land: New World Epidemics in a Global Perspective |vauthors=Alchon S |publisher=University of New Mexico Press |year=2003 |isbn=978-0-8263-2871-7 |page=62 |access-date=9 March 2019}}</ref>[[File:The Triumph of Death P001393.jpg|thumb|upright=1.3|[[Pieter Brueghel the Elder|Pieter Bruegel]]'s ''[[The Triumph of Death]]'' ({{circa|1562}}) reflects the social upheaval and terror that followed the plague, which devastated medieval Europe.]]
[[File:1918 Headlines from Chicago newspapers - Spanish flu - 1918 influenza pandemic.jpg| thumb|upright=1.5|1918 Chicago newspaper headlines reflect mitigation strategies for the [[Spanish flu]], such as increased ventilation, arrests for "open-face sneezes and coughs", sequenced inoculations, limitations on crowd size, selective closing of businesses, curfews, and lockdowns.<ref name=USAtoday_20201122>{{cite news | vauthors = Hauck G |others=Graphics by Karl Gelles|title=We're celebrating Thanksgiving amid a pandemic. Here's how we did it in 1918 – and what happened next |url=https://www.usatoday.com/in-depth/news/nation/2020/11/21/covid-and-thanksgiving-how-we-celebrated-during-1918-flu-pandemic/6264231002/ |work=[[USA Today]] |date=22 November 2020 |archive-url=https://web.archive.org/web/20201121183814/https://eu.usatoday.com/in-depth/news/nation/2020/11/21/covid-and-thanksgiving-how-we-celebrated-during-1918-flu-pandemic/6264231002/ |archive-date=21 November 2020 |url-status=live }}</ref>]]

It is assumed that, prior to the [[Neolithic Revolution]] around 10,000 BC, disease outbreaks were limited to a single family or clan, and did not spread widely before dying out. The domestication of animals increased human-animal contact, increasing the possibility of zoonotic infections. The advent of agriculture, and trade between settled groups, made it possible for pathogens to spread widely. As the population increased, contact between groups became more frequent. A history of epidemics maintained by the Chinese Empire from 243 B.C. to 1911 A.C. shows an approximate correlation between the frequency of epidemics and the growth of the population.<ref name=":03">{{cite journal | vauthors = Høiby N | title = Pandemics: past, present, future: That is like choosing between cholera and plague | journal = APMIS | volume = 129 | issue = 7 | pages = 352–371 | date = July 2021 | pmid = 33244837 | pmc = 7753327 | doi = 10.1111/apm.13098 }}</ref>

Here is an incomplete list of known epidemics which have spread widely enough to merit the title "pandemic".
* [[Plague of Athens]] (430 to 426 BC): During the [[Peloponnesian War]], an epidemic killed a quarter of the Athenian troops and a quarter of the population. This disease fatally weakened the dominance of [[Athens]], but the sheer virulence of the disease prevented its wider spread; i.e., it killed off its hosts at a rate faster than they could spread it. The exact cause of the plague was unknown for many years. In January 2006, researchers from the [[University of Athens]] analyzed [[teeth]] recovered from a [[mass grave]] underneath the city and confirmed the presence of [[bacteria]] responsible for [[typhoid fever]].<ref>[http://www.sciam.com/article.cfm?articleID=000BF619-9B78-13D6-9B7883414B7F0135&chanID=sa003 "Ancient Athenian Plague Proves to Be Typhoid"]. ''Scientific American.'' 25 January 2006.</ref>
* [[Antonine Plague]] (165 to 180 AD): Possibly measles or smallpox brought to the Italian peninsula by soldiers returning from the Near East, it killed a quarter of those infected, up to five million in total.<ref>[http://news.bbc.co.uk/2/hi/health/4381924.stm Past pandemics that ravaged Europe]. ''BBC News'', 7{{nbsp}}November. 2005</ref>
* [[Plague of Cyprian]] (251–266 AD): A second outbreak of what may have been the same disease as the Antonine Plague killed (it was said) 5,000 people a day in [[Rome]].<ref>{{cite web | vauthors = Horgan J |title=Plague of Cyprian, 250–270 CE |url=https://www.worldhistory.org/article/992/plague-of-cyprian-250-270-ce/ |access-date=16 July 2023 |website=World History Encyclopedia }}</ref>
* [[Plague of Justinian]] (541 to 549 AD): Also known as the ''First Plague Pandemic''. This epidemic started in [[Egypt]] and reached [[Constantinople]] the following spring, killing (according to the Byzantine chronicler [[Procopius]]) 10,000 a day at its height, and perhaps 40% of the city's inhabitants. The plague went on to eliminate a quarter to half the [[human population]] of the known world and was identified in 2013 as being caused by [[bubonic plague]].<ref>{{cite web |date=20 May 2013 |title=Modern lab reaches across the ages to resolve plague DNA debate |url=http://phys.org/news/2013-05-modern-lab-ages-plague-dna.html |website=phys.org}}</ref><ref>{{cite book | vauthors = Little LK |title=Plague and the end of Antiquity: the pandemic of 541-750 |date=2007 |publisher=Cambridge University Press |location=Cambridge (Mass.) |isbn=978-0-521-84639-4}}</ref>
* [[Black Death]] (1331 to 1353): Also known as the ''Second Plague Pandemic.'' The total number of deaths worldwide is estimated at 75 to 200 million. Starting in Asia, the disease reached the Mediterranean and western Europe in 1348 (possibly from Italian merchants fleeing fighting in [[Crimea]]) and killed an estimated 20 to 30 million Europeans in six years;<ref>[http://www.medhunters.com/articles/deathOnAGrandScale.html Death on a Grand Scale]. ''MedHunters.''</ref> a third of the total population,<ref>Stéphane Barry and Norbert Gualde, in ''[[L'Histoire]]'' No. 310, June 2006, pp. 45–46, say "between one-third and two-thirds"; Robert Gottfried (1983). "Black Death" in ''[[Dictionary of the Middle Ages]]'', volume 2, pp. 257–267, says "between 25 and 45&nbsp;percent".</ref> and up to a half in the worst-affected urban areas.<ref>{{cite EB1911 |wstitle=Plague |volume=21 |pages=693–705}}</ref> It was the first of a cycle of European [[Second plague pandemic|plague epidemics]] that continued until the 18th century;<ref>{{cite web |url=http://urbanrim.org.uk/plague%20list.htm |title=A List of National Epidemics of Plague in England 1348–1665 |publisher=Urbanrim.org.uk |date=4 August 2010 |access-date=26 August 2010 |archive-url=https://web.archive.org/web/20090508010316/http://urbanrim.org.uk/plague%20list.htm |archive-date=8 May 2009 |url-status=dead }}</ref> there were more than 100 plague epidemics in Europe during this period,<ref>{{cite news |url=https://www.theguardian.com/uk/2004/may/16/health.books |title=Black Death blamed on man, not rats |newspaper=The Observer | vauthors = Revill J |date= 16 May 2004|access-date=3 November 2008 | location=London}}</ref> including the [[Great Plague of London]] of 1665–66 which killed approximately 100,000 people, 20% of London's population.<ref>[http://ocp.hul.harvard.edu/contagion/plague.html The Great Plague of London, 1665]. ''The Harvard University Library, Open Collections Program: Contagion.''</ref>
* [[1817–1824 cholera pandemic]]. Previously endemic in the [[Indian subcontinent]], the pandemic began in [[Bengal]], then spread across India by 1820. The deaths of 10,000 British troops were documented - it is assumed that tens of thousands of Indians must have died.<ref name="cbc-cholera">[https://www.cbc.ca/news/science/cholera-s-seven-pandemics-1.758504 Cholera's seven pandemics], cbc.ca, December 2, 2008.</ref> The disease spread as far as China, [[Indonesia]] (where more than 100,000 people succumbed on the island of [[Java]] alone)<ref>{{Cite web |title=Cholera - Pandemic, Waterborne, 19th Century {{!}} Britannica |url=https://www.britannica.com/science/cholera/Cholera-through-history |access-date=2023-08-27 |website=www.britannica.com |language=en}}</ref> and the [[Caspian Sea]] before receding. Subsequent cholera pandemics during the 19th century are estimated to have caused many millions of deaths globally.<ref>{{Cite journal |last=Pollitzer |first=R. |date=1954 |title=Cholera studies |journal=Bulletin of the World Health Organization |volume=10 |issue=3 |pages=421–461 |issn=0042-9686 |pmc=2542143 |pmid=13160764}}</ref><ref>{{Cite book |last=McNeill |first=William Hardy |title=Plagues and peoples |date=1998 |publisher=Anchor Books |isbn=978-0-385-12122-4 |edition=Reprint [der Ausg.] Garden City, NY, 1976 |location=New York}}</ref>[[File:Chevalier Roze à la Tourette - 1720.PNG|thumb|[[Great Plague of Marseille]] in 1720 killed a total of 100,000 people]]
* [[Third plague pandemic]] (1855–1960): Starting in China, it is estimated to have caused over 12 million deaths in total, the majority of them in India.<ref>{{cite web |title=History's Seven Deadliest Plagues {{!}} Gavi, the Vaccine Alliance |url=https://www.gavi.org/vaccineswork/historys-seven-deadliest-plagues |access-date=16 July 2023 |website=www.gavi.org }}</ref><ref>{{cite web |url=https://www.who.int/vaccine_research/diseases/zoonotic/en/index4.html |title=Zoonotic Infections: Plague |publisher=World Health Organization |archive-url=https://web.archive.org/web/20090420003315/http://www.who.int/vaccine_research/diseases/zoonotic/en/index4.html |archive-date=20 April 2009 |access-date=5 July 2014}}</ref> During this pandemic, the United States saw its first outbreak: the [[San Francisco plague of 1900–1904]].<ref>[https://www.pbs.org/wgbh/aso/databank/entries/dm00bu.html Bubonic plague hits San Francisco 1900–1909]. ''A Science Odyssey. Public Broadcasting Service (PBS).''</ref> The causative bacterium, ''[[Yersinia pestis]]'', was identified in 1894.<ref>{{cite journal | vauthors = Yersin A |year=1894 |title=La peste bubonique à Hong-Kong |url=https://www.biodiversitylibrary.org/item/23590#page/692/mode/1up |journal=Annales de l'Institut Pasteur |volume=8 |pages=662–67 |language=fr}}</ref> The association with fleas, and in particular rat fleas in urban environments, led to effective control measures. The pandemic was considered to be over in 1959 when annual deaths due to plague dropped below 200. The disease is nevertheless present in the rat population worldwide and isolated human cases still occur.<ref>{{cite web |date=7 July 2022 |title=Plague |url=https://www.who.int/news-room/fact-sheets/detail/plague |access-date=16 July 2023 |website=World Health Organization }}</ref>
* The 1918–1920 [[Spanish flu]] infected half a billion people<ref name="Taubenberger">{{cite journal |vauthors=Taubenberger JK, Morens DM |date=January 2006 |title=1918 Influenza: the mother of all pandemics |url=https://www.cdc.gov/ncidod/eid/vol12no01/05-0979.htm |url-status=dead |journal=Emerging Infectious Diseases |volume=12 |issue=1 |pages=15–22 |doi=10.3201/eid1201.050979 |pmc=3291398 |pmid=16494711 |archive-url=https://web.archive.org/web/20091006002531/http://www.cdc.gov/ncidod/eid/vol12no01/05-0979.htm |archive-date=6 October 2009 |access-date=7 September 2017}}</ref> around the world, including on remote [[Pacific islands]] and in the [[Arctic]]—killing 20 to 100 million.<ref name="Taubenberger" /><ref>{{cite web| title=Historical Estimates of World Population| url=https://www.census.gov/population/international/data/worldpop/table_history.php| archive-url=https://web.archive.org/web/20120709092946/https://www.census.gov/population/international/data/worldpop/table_history.php| url-status=dead| archive-date=9 July 2012| access-date=29 March 2013}}</ref> Most influenza outbreaks disproportionately kill the very young and the very old, but the 1918 pandemic had an unusually high mortality rate for young adults.<ref>{{cite journal | vauthors = Gagnon A, Miller MS, Hallman SA, Bourbeau R, Herring DA, Earn DJ, Madrenas J | title = Age-specific mortality during the 1918 influenza pandemic: unravelling the mystery of high young adult mortality | journal = PLOS ONE | volume = 8 | issue = 8 | pages = e69586 | year = 2013 | pmid = 23940526 | pmc = 3734171 | doi = 10.1371/journal.pone.0069586 | bibcode = 2013PLoSO...869586G | doi-access = free }}</ref> It killed more people in 25 weeks than AIDS did in its first 25 years.<ref>{{cite web|url=https://virus.stanford.edu/uda/|title=The 1918 Influenza Pandemic|website=virus.stanford.edu}}</ref><ref>{{cite web | archive-url = https://web.archive.org/web/20100127100727/http://www.channel4.com/news/articles/world/spanish%20flu%20facts/111285 | archive-date = 27 January 2010 | url-status = dead | url = http://www.channel4.com/news/articles/world/spanish%20flu%20facts/111285 | title = Spanish flu facts | work = Channel 4 News }}</ref> Mass troop movements and close quarters during World War{{nbsp}}I caused it to spread and [[mutation|mutate]] faster, and the susceptibility of soldiers to the flu may have been increased by stress, [[malnourishment]] and [[chemical attack]]s.<ref>{{cite book| vauthors = Qureshi AI | title=Ebola Virus Disease: From Origin to Outbreak| url=https://books.google.com/books?id=7zyXCgAAQBAJ&q=Ebola+Virus+Disease:+From+Origin+to+Outbreak+Adnan+1918+pandemic&pg=PA42| page=42| publisher=Academic Press| date=2016| isbn=978-0128042427}}</ref> Improved transportation systems made it easier for soldiers, sailors and civilian travelers to spread the disease.<ref>[https://web.archive.org/web/20131211093810/http://www.xtimeline.com/evt/view.aspx?id=65022 Spanish flu strikes during World War I], 14 January 2010</ref>

=== Pandemics in indigenous populations ===
{{See also|Native American disease and epidemics|Smallpox in Australia|History of smallpox in Mexico}}
[[File:FlorentineCodex BK12 F54 smallpox.jpg|thumb|Aztecs dying of smallpox, ''[[Florentine Codex]]'' (compiled 1540–1585)]]

Beginning from the Middle Ages, encounters between European settlers and native populations in the rest of the world often introduced epidemics of extraordinary virulence. Settlers introduced novel diseases which were endemic in Europe, such as [[smallpox]], [[measles]], [[pertussis]] and [[influenza]], to which the [[indigenous peoples]] had no immunity.<ref>{{cite web |title=The Story Of ... Smallpox—and other Deadly Eurasian Germs |url=https://www.pbs.org/gunsgermssteel/variables/smallpox.html |access-date=26 August 2010 |publisher=Pbs.org}}</ref><ref>{{cite web |title=Stacy Goodling, "Effects of European Diseases on the Inhabitants of the New World" |url=http://www.millersville.edu/~columbus/papers/goodling.html |url-status=dead |archive-url=https://web.archive.org/web/20080510163413/http://www.millersville.edu/~columbus/papers/goodling.html |archive-date=10 May 2008}}</ref> The Europeans infected with such diseases typically carried them in a [[Dormancy|dormant state]], were actively infected but [[asymptomatic]], or had only mild symptoms.<ref name="Francis 2005">{{cite book | vauthors = Francis JM |title=Iberia and the Americas culture, politics, and history: A Multidisciplinary Encyclopedia |publisher=ABC-CLIO |year=2005 |isbn=1851094210 |location=Santa Barbara, California}}</ref>

Smallpox was the most destructive disease that was brought by Europeans to the Native Americans, both in terms of [[morbidity]] and mortality. The first well-documented smallpox epidemic in the Americas began in [[Hispaniola]] in late 1518 and soon spread to Mexico.<ref name="Francis 2005" /> Estimates of mortality range from one-quarter to one-half of the population of central Mexico.<ref name=":04">{{cite book | vauthors = Hays J |title=Epidemics and Pandemics: Their Impacts on Human History. |publisher=Bloomsbury Publishing |year=2005 |isbn=9781851096589}}</ref> It is estimated that over the 100 years after European arrival in 1492, the indigenous population of the Americas dropped from 60 million to only 6 million, due to a combination of disease, war, and famine. The majority these deaths are attributed to successive waves of introduced diseases such as smallpox, measles, and typhoid fever.<ref>{{cite web | vauthors = Gunderman R |title=How smallpox devastated the Aztecs – and helped Spain conquer an American civilization 500 years ago |url=http://theconversation.com/how-smallpox-devastated-the-aztecs-and-helped-spain-conquer-an-american-civilization-500-years-ago-111579 |access-date=1 December 2022 |website=The Conversation |date=19 February 2019 }}</ref><ref>{{cite web | vauthors = Koch A |date=1 December 2019 |title='Great Dying' in Americas disturbed Earth's climate |url=https://www.ucl.ac.uk/news/2019/feb/great-dying-americas-disturbed-earths-climate |access-date=26 July 2023 |website=University College London – News }}</ref><ref name="Agence France-Presse">{{cite news |date=18 January 2018 |title=500 years later, scientists discover what probably killed the Aztecs |work=The Guardian |agency=[[Agence France-Presse|AFP]] |url=https://www.theguardian.com/world/2018/jan/16/mexico-500-years-later-scientists-discover-what-killed-the-aztecs |access-date=16 January 2018}}</ref>

In [[Australia]], smallpox was introduced by European settlers in 1789 devastating the [[Aboriginal Australians|Australian Aboriginal]] population, killing an estimated 50% of those infected with the disease during the first decades of colonisation.<ref>{{cite book | vauthors = Dowling P |title=Fatal contact: How epidemics nearly wiped out Australia's first peoples |publisher=Clayton, Victoria: Monash University Publishing |year=2021 |isbn=9781922464460 |pages=30–31, 60–63}}</ref> In the early 1800s, measles, smallpox and intertribal warfare killed an estimated 20,000 New Zealand [[Māori people|Māori]].<ref>{{cite web |date=31 March 1998 |title=New Zealand Historical Perspective |url=http://www.canr.msu.edu/overseas/nzenvironsci/infopart2.htm |url-status=dead |archive-url=https://web.archive.org/web/20100612021507/http://www.canr.msu.edu/overseas/nzenvironsci/infopart2.htm |archive-date=12 June 2010 |access-date=26 August 2010 |publisher=Canr.msu.edu}}</ref>

In 1848–49, as many as 40,000 out of 150,000 [[Hawaii]]ans are estimated to have died of [[measles]], [[whooping cough]] and [[influenza]]. Measles killed more than 40,000 [[Fiji]]ans, approximately one-third of the population, in 1875,<ref>{{cite journal | vauthors = Derrick RA |date=18 April 1955 |title=Fiji's darkest hour – an account of the Measles Epidemic of 1875 |url=http://www.justpacific.com/fiji/full-text/Derrick%E2%80%94Measles.pdf |journal=Transactions and Proceedings of the Fiji Society |volume=for the years 1955–1957 |pages=6(1): 3–16}}</ref> and in the early 19th century devastated the [[Great Andamanese]] population.<ref>{{cite web | url = http://news.bbc.co.uk/2/hi/south_asia/4987406.stm | title = Measles hits rare Andaman tribe | work = BBC News | date = 16 May 2006 }}</ref> In [[Hokkaido]], an epidemic of smallpox introduced by Japanese settlers is estimated to have killed 34% of the native [[Ainu people|Ainu]] population in 1845.<ref>{{cite book | vauthors = Walker BL |url=https://books.google.com/books?id=D5iOcHB3h5AC |title=The Conquest of Ainu Lands: Ecology and Culture in Japanese Expansion, 1590–1800 |date=2001 |publisher=University of California Press |isbn=978-0-520-93299-9 }}</ref>

== Concerns about future pandemics ==
{{See also|Pandemic prevention}}
Prevention of future pandemics requires steps to identify future causes of pandemics and to take preventive measures before the disease moves uncontrollably into the human population.

For example, influenza is a rapidly evolving disease which has caused pandemics in the past and has the potential to cause future pandemics. WHO collates the findings of 144 national influenza centres worldwide which monitor emerging flu viruses. Virus variants which are assessed as likely to represent a significant risk are identified and can then be incorporated into the next seasonal influenza vaccine program.<ref>{{cite web |date=3 November 2022 |title=Selecting Viruses for the Seasonal Flu Vaccine |url=https://www.cdc.gov/flu/prevent/vaccine-selection.htm |access-date=30 June 2023 |website=Centers for Disease Control and Prevention }}</ref>

In a press conference on 28 December 2020, Mike Ryan, head of the WHO Emergencies Program, and other officials said the current COVID-19 pandemic was "not necessarily the big one" and "the next pandemic may be more severe." They called for preparation.<ref>{{cite news|date=29 December 2020|title=WHO official: 'Next pandemic may be more severe'|url=https://arab.news/yx8p9|access-date=30 December 2020|website=Arab News}}</ref> WHO and the UN have warned the world must tackle the cause of pandemics and not just the health and economic symptoms.<ref>{{cite web| vauthors = Carrington D |date=9 March 2021|title=Inaction leaves world playing 'Russian roulette' with pandemics, say experts|url=http://www.theguardian.com/environment/2021/mar/09/inaction-leaves-world-playing-russian-roulette-pandemics-experts|access-date=10 March 2021|website=The Guardian}}</ref>

=== Diseases with pandemic potential ===
{{Further|Emerging infectious disease}}There is always a possibility that a disease which has caused epidemics in the past may return in the future.<ref name=":03"/> It is also possible that little known diseases may become more virulent; in order to encourage research, a number of organisations which monitor global health have drawn up lists of diseases which may have pandemic potential; see table below.{{Efn|As of June 2023, the WHO is reviewing its list}}
{| class="wikitable"
|+List of potential pandemic diseases according to global health organisations
!
![[World Health Organization|WHO]]<ref>{{cite web |date= |title=Prioritizing diseases for research and development in emergency contexts (Published 2018, revision in progress 2023) |url=https://www.who.int/activities/prioritizing-diseases-for-research-and-development-in-emergency-contexts |access-date=23 June 2023 |website=World Health Organization }}</ref>
![[Coalition for Epidemic Preparedness Innovations|CEPI]]<ref>{{cite web |date=23 June 2023 |title=Targeting diseases with epidemic and pandemic potential |url=https://cepi.net/research_dev/priority-diseases/ |access-date=23 June 2023 |website=CEPI, Coalition for Epidemic Preparedness Innovations }}</ref>
![[GAVI]]<ref>{{cite web |date=7 May 2020 |title=10 infectious diseases that could be the next pandemic {{!}} Gavi, the Vaccine Alliance |url=https://www.gavi.org/vaccineswork/10-infectious-diseases-could-be-next-pandemic |access-date=23 June 2023 |website=Gavi, the Vaccine Alliance }}</ref>
|-
|[[Chikungunya]]
|
|Yes
|
|-
|[[COVID-19]]
|Yes
|
|
|-
|[[Crimean–Congo hemorrhagic fever|Crimean-Congo haemorrhagic fever]]
|Yes
|
|Yes
|-
|[[Ebola|Ebola virus disease]]
|Yes
|Yes
|Yes
|-
|[[Lassa fever]]
|Yes
|Yes
|Yes
|-
|[[Marburg virus disease]]
|Yes
|
|Yes
|-
|[[Mpox]]
|
|
|Yes
|-
|[[MERS|Middle East respiratory syndrome]] coronavirus (MERS-CoV)
|Yes
|
|Yes
|-
|[[Nipah virus infection|Nipah]] and other [[Henipavirus|henipaviral]] diseases
|Yes
|Yes
|Yes
|-
|[[Rift Valley fever]]
|Yes
|Yes
|Yes
|-
|[[SARS|Severe Acute Respiratory Syndrome]] (SARS)
|Yes
|Yes
|Yes
|-
|[[Zika fever|Zika]]
|Yes
|
|Yes
|-
|[[Disease X]]{{Efn|Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease.}}
|Yes
|Yes
|
|}

==== Coronaviruses ====
{{Further|2002–2004 SARS outbreak|COVID-19 pandemic}}
[[File:Coronavirus virion.jpg|thumb|A generic coronavirus illustration]]
[[Coronavirus]] diseases are a family of usually mild illnesses in humans, including those such as the [[common cold]], that have resulted in outbreaks and pandemics such as the [[1889–1890 pandemic|1889-1890 pandemic]],<ref>{{cite journal | vauthors = Berche P | title = The enigma of the 1889 Russian flu pandemic: A coronavirus? | journal = Presse Médicale | volume = 51 | issue = 3 | pages = 104111 | date = September 2022 | pmid = 35124103 | pmc = 8813723 | doi = 10.1016/j.lpm.2022.104111 }}</ref><ref>{{Cite news |date=2022-02-14 |title=An Undiscovered Coronavirus? The Mystery of the 'Russian Flu' (Published 2022) |work=The New York Times |language=en |url=https://www.nytimes.com/2022/02/14/health/russian-flu-coronavirus.html |access-date=2023-07-29 |last1=Kolata |first1=Gina }}</ref> the [[2002–2004 SARS outbreak]], ''[[Middle East respiratory syndrome–related coronavirus]]'' and the [[COVID-19 pandemic]]. There is widespread concern that members of the coronavirus family, particularly [[SARS]] and MERS have the potential to cause future pandemics.<ref>{{cite web | vauthors = Heymann D, Ross E, Wallace J |date=23 February 2022 |title=The next pandemic – when could it be? |url=https://www.chathamhouse.org/2022/02/next-pandemic-when-could-it-be |access-date=24 July 2023 |website=Chatham House, The Royal Institute of International Affairs}}</ref> Many human coronaviruses have zoonotic origins, their with natural reservoir in bats or rodents,<ref name=":82">{{cite journal | vauthors = Forni D, Cagliani R, Clerici M, Sironi M | title = Molecular Evolution of Human Coronavirus Genomes | journal = Trends in Microbiology | volume = 25 | issue = 1 | pages = 35–48 | date = January 2017 | pmid = 27743750 | pmc = 7111218 | doi = 10.1016/j.tim.2016.09.001 | quote = Specifically, all HCoVs are thought to have a bat origin, with the exception of lineage A beta-CoVs, which may have reservoirs in rodents [2]. }}</ref> leading to concerns for future [[Spillover infection|spillover]] events.<ref>{{cite journal | vauthors = Holmes EC | title = COVID-19-lessons for zoonotic disease | journal = Science | volume = 375 | issue = 6585 | pages = 1114–1115 | date = March 2022 | pmid = 35271309 | doi = 10.1126/science.abn2222 | bibcode = 2022Sci...375.1114H | s2cid = 247384213 }}</ref>

Following the end of the COVID-19 pandemic Public Health Emergency of International Concern deceleration by WHO, WHO Director General [[Tedros Adhanom Ghebreyesus|Tedros Ghebreyesus]] stated he would not hesitate to re-declare COVID-19 a PHEIC should the global situation worsen in the coming months or years.

==== Influenza ====
{{Main|Influenza pandemic}}[[File:Barack Obama being briefed on swine flu oubreak 4-29.jpg|thumb|President [[Barack Obama]] is briefed in the Situation Room about the [[2009 swine flu pandemic|2009 flu pandemic]], which killed as many as 17,000 Americans.<ref>{{cite news |date=12 February 2010 |title=Swine flu has killed up to 17,000 in U.S.: report |work=Reuters |url=https://www.reuters.com/article/us-flu-usa/swine-flu-has-killed-up-to-17000-in-u-s-report-idUSN1223579720100212}}</ref>]][[Influenza]] was first described by the Greek physician [[Hippocrates]] in 412{{nbsp}}BC.<ref>{{cite web |title=50 Years of Influenza Surveillance |url=http://who.int/inf-pr-1999/en/pr99-11.html |archive-url=https://web.archive.org/web/20090501165850/http://www.who.int/inf-pr-1999/en/pr99-11.html |archive-date=1 May 2009 |work=World Health Organization}}</ref> Since the Middle Ages, influenza pandemics have been recorded every 10 to 30 years as the virus mutates to evade immunity.<ref>{{cite journal |vauthors=Potter CW |date=October 2001 |title=A history of influenza |journal=Journal of Applied Microbiology |volume=91 |issue=4 |pages=572–579 |doi=10.1046/j.1365-2672.2001.01492.x |pmid=11576290 |s2cid=26392163 |doi-access=free}}</ref><ref>{{cite web |date=12 December 2022 |title=How Flu Viruses Can Change |url=https://www.cdc.gov/flu/about/viruses/change.htm |access-date=12 July 2023 |website=Centers for Disease Control and Prevention}}</ref>

Influenza is an [[Endemic (epidemiology)|endemic disease]], with a fairly constant number of cases which vary seasonally and can, to a certain extent, be predicted.<ref>{{cite web |date=2 May 2023 |title=Key Facts About Influenza (Flu) |url=https://www.cdc.gov/flu/about/keyfacts.htm |access-date=12 July 2023 |website=Centers for Disease Control and Prevention}}</ref> In a typical year, 5–15% of the population contracts influenza. There are 3–5 million severe cases annually, with up to 650,000 respiratory-related deaths globally each year.<ref>{{cite web |title=Influenza (Seasonal) |url=https://www.who.int/news-room/fact-sheets/detail/influenza-(seasonal) |access-date=12 July 2023 |website=World Health Organization }}</ref> The [[1889–1890 pandemic]] is estimated to have caused around a million fatalities,<ref name="Shally-Jensen_2010">{{cite book |title=Encyclopedia of Contemporary American Social Issues |date=2010 |publisher=[[ABC-CLIO]] |isbn=978-0-31339205-4 | veditors = Shally-Jensen M |volume=2 |page=1510 |chapter=Influenza |quote=The Asiatic flu killed roughly one million individuals |chapter-url=https://books.google.com/books?id=BjKWfAz0tx4C&pg=PA1510}}</ref> and the "[[Spanish flu]]" of 1918–1920 eventually infected about one-third of the [[world's population]] and caused an estimated 50{{nbsp}}million fatalities.<ref name="Taubenberger" />

The [[Global Influenza Surveillance and Response System]] is a global network of laboratories that has for purpose to monitor the spread of [[influenza]] with the aim to provide WHO with influenza control information.<ref name="Fange">{{cite book | vauthors = Lee K, Fang J |url=https://books.google.com/books?id=9zCEmpopjG0C&dq=%22WHO%22+%22GISRS+is+a%22&pg=PA163 |title=Historical Dictionary of the World Health Organization |year=2013 | publisher=Rowman & Littlefield |isbn=9780810878587}}</ref> More than two million respiratory specimens are tested by GISRS annually to monitor the spread and evolution of influenza viruses through a network of about 150 laboratories in 114 countries representing 91% of the world's population.<ref name="Leveraging">{{cite journal | vauthors = Broor S, Campbell H, Hirve S, Hague S, Jackson S, Moen A, Nair H, Palekar R, Rajatonirina S, Smith PG, Venter M, Wairagkar N, Zambon M, Ziegler T, Zhang W | display-authors = 6 | title = Leveraging the Global Influenza Surveillance and Response System for global respiratory syncytial virus surveillance-opportunities and challenges | journal = Influenza and Other Respiratory Viruses | volume = 14 | issue = 6 | pages = 622–629 | date = November 2020 | pmid = 31444997 | pmc = 7578328 | doi = 10.1111/irv.12672 | doi-access = free }}{{CC-notice|by4|url=https://onlinelibrary.wiley.com/doi/full/10.1111/irv.12672}}</ref>

=== Antibiotic resistance ===
{{Main|Antibiotic resistance}}

Antibiotic-resistant microorganisms, which sometimes are referred to as "[[Antibiotic resistance|superbug]]s", may contribute to the re-emergence of diseases with pandemic potential that are currently well controlled.<ref>{{cite web | url = http://www.pasteur.fr/actu/presse/press/07pesteTIGR_E.htm | title = Researchers sound the alarm: the multidrug resistance of the plague bacillus could spread | archive-url = https://web.archive.org/web/20071014012153/http://www.pasteur.fr/actu/presse/press/07pesteTIGR_E.htm| archive-date = 14 October 2007 | work = Pasteur.fr }}</ref>

For example, cases of tuberculosis that are resistant to traditionally effective treatments remain a cause of great concern to health professionals. Every year, nearly half a million new cases of [[multidrug-resistant tuberculosis]] (MDR-TB) are estimated to occur worldwide.<ref>[https://web.archive.org/web/20090406170131/http://www.who.int/mediacentre/news/releases/2009/tuberculosis_drug_resistant_20090402/en/index.html Health ministers to accelerate efforts against drug-resistant TB]. ''World Health Organization.''</ref> China and India have the highest rate of MDR-TB.<ref>[https://www.theguardian.com/society/2009/apr/01/bill-gates-tb-timebomb-china Bill Gates joins Chinese government in tackling TB 'timebomb']. ''Guardian.co.uk''. 1 April 2009</ref> WHO reports that approximately 50 million people worldwide are infected with MDR-TB, with 79 percent of those cases resistant to three or more antibiotics. Extensively drug-resistant tuberculosis ([[XDR TB|XDR-TB]]) was first identified in Africa in 2006 and subsequently discovered to exist in 49 countries. During 2021 there were estimated to be around 25,000 cases XDR-TB worldwide.<ref>{{cite web |title=Global Tuberculosis Report |url=https://www.who.int/teams/global-tuberculosis-programme/tb-reports |access-date=30 June 2023 |website=World Health Organization }}</ref>

In the past 20 years, other common bacteria including ''[[Staphylococcus aureus]]'', ''[[Serratia marcescens]]'' and ''[[Enterococcus]]'', have developed resistance to a wide range of [[antibiotics]]. Antibiotic-resistant organisms have become an important cause of healthcare-associated ([[Hospital-acquired infection|nosocomial]]) infections.<ref name=":8">{{cite journal |vauthors=Murray CJ, Ikuta KS, Sharara F, Swetschinski L, Aguilar GR, Gray A, etal |date=February 2022 |title=Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis |journal=Lancet |volume=399 |issue=10325 |pages=629–655 |doi=10.1016/S0140-6736(21)02724-0 |pmc=8841637 |pmid=35065702 |s2cid=246077406 |collaboration=Antimicrobial Resistance Collaborators}}</ref>

=== Climate change ===
{{Further|Effects of global warming on human health#Impact on infectious diseases}}
[[File:Aedes_aegypti_CDC9253.tif|thumb|''[[Aedes aegypti]]'', the mosquito that is the vector for [[dengue]] transmission.]]

There are two groups of infectious diseases that may be affected by climate change. The first group are [[vector-borne disease]]s which are transmitted via insects such as mosquitos or ticks.<ref>{{Cite book |last=Intergovernmental Panel on Climate Change (IPCC) |url=https://www.cambridge.org/core/product/identifier/9781009325844/type/book |title=Climate Change 2022 – Impacts, Adaptation and Vulnerability: Working Group II Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change |date=29 June 2023 |publisher=Cambridge University Press |isbn=978-1-009-32584-4 |edition=1 |pages=1041–1170 |doi=10.1017/9781009325844.009}}</ref> Some of these diseases, such as [[malaria]], [[yellow fever]], and [[dengue fever]], can have potentially severe health consequences. Climate can affect the distribution of these diseases due to the changing geographic range of their vectors, with the potential to cause serious outbreaks in areas where the disease has not previously been known.<ref name="The Mosquito's Bite">{{cite book | vauthors = Epstein PR, Ferber D |url= https://archive.org/details/unset0000unse_c1j4/page/29 |title=Changing Planet, Changing Health: How the Climate Crisis Threatens Our Health and what We Can Do about it |publisher=University of California Press |year=2011 |isbn=978-0-520-26909-5 |pages=[https://archive.org/details/unset0000unse_c1j4/page/29 29–61] |chapter=The Mosquito's Bite |chapter-url=https://books.google.com/books?id=nnOkFhXo8rEC&pg=PA29}}</ref> The other group comprises [[Waterborne diseases|water-borne]] diseases such as cholera, dysentery, and typhoid which may increase in prevalence due to changes in rainfall patterns.<ref>{{Cite journal | vauthors = Jung YJ, Khant NA, Kim H, Namkoong S |date=January 2023 |title=Impact of Climate Change on Waterborne Diseases: Directions towards Sustainability |journal=Water |language=en |volume=15 |issue=7 |pages=1298 |doi=10.3390/w15071298 |issn=2073-4441 |doi-access=free |bibcode=2023Water..15.1298J }}</ref>

=== Encroaching into wildlands ===
{{Further|Zoonosis#Biodiversity loss and environmental degradation|Human–wildlife conflict|Wildland–urban interface|Urban sprawl}}

The October 2020 'era of pandemics' report by the [[United Nations]]' [[Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services]], written by 22 experts in a variety of fields, said the anthropogenic destruction of [[biodiversity]] is paving the way to the pandemic era and could result in as many as 850,000 viruses being transmitted from animals—in particular [[birds]] and [[mammals]]—to humans. The [[Overconsumption|"exponential rise" in consumption]] and trade of commodities such as [[meat]], [[palm oil]], and metals, largely facilitated by developed nations, and a [[Population growth|growing human population]], are the primary drivers of this destruction. According to [[Peter Daszak]], the chair of the group who produced the report, "there is no great mystery about the cause of the Covid-19 pandemic or any modern pandemic. The same human activities that drive [[climate change and biodiversity loss]] also drive pandemic risk through their impacts on our environment." Proposed policy options from the report include taxing meat production and consumption, cracking down on the illegal wildlife trade, removing high-risk species from the legal wildlife trade, eliminating subsidies to businesses that are harmful to the natural world, and establishing a global surveillance network.<ref>{{cite news |date=29 October 2020 |title=UN report says up to 850,000 animal viruses could be caught by humans, unless we protect nature |work=[[The Conversation (website)|The Conversation]] |url=https://theconversation.com/un-report-says-up-to-850-000-animal-viruses-could-be-caught-by-humans-unless-we-protect-nature-148911 |access-date=1 December 2020 |vauthors=Woolaston K, Fisher JL}}</ref><ref>{{cite news |date=29 October 2020 |title=Protecting nature is vital to escape 'era of pandemics' – report |work=The Guardian |url=https://www.theguardian.com/environment/2020/oct/29/protecting-nature-vital-pandemics-report-outbreaks-wild |access-date=1 December 2020 |vauthors=Carrington D}}</ref><ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |date=29 October 2020 |title=Escaping the 'Era of Pandemics': experts warn worse crises to come; offer options to reduce risk |work=EurekAlert! |url=https://www.eurekalert.org/pub_releases/2020-10/tca-et102820.php |access-date=1 December 2020}}</ref>

In June 2021, a team of scientists assembled by the [[Harvard Medical School Center for Health and the Global Environment]] warned that the primary cause of pandemics so far, the anthropogenic destruction of the natural world through such activities including [[deforestation]] and [[hunting]], is being ignored by world leaders.<ref>{{cite news |date=4 June 2021 |title=World leaders 'ignoring' role of the destruction of nature in causing pandemics |work=The Guardian |location= |url=https://www.theguardian.com/world/2021/jun/04/end-destruction-of-nature-to-stop-future-pandemics-say-scientists |access-date=4 June 2021 |vauthors=Carrington D}}</ref>

=== Melting permafrost ===
[[Permafrost]] covers a fifth of the northern hemisphere and is made up of soil that has been kept at temperatures below freezing for long periods. Viable samples of viruses have been recovered from thawing permafrost, after having been frozen for many years, sometimes for millennia. There is a remote possibility that a thawed pathogen could infect humans or animals.<ref>{{Cite journal |last1=Alempic |first1=Jean-Marie |last2=Lartigue |first2=Audrey |last3=Goncharov |first3=Artemiy E. |last4=Grosse |first4=Guido |last5=Strauss |first5=Jens |last6=Tikhonov |first6=Alexey N. |last7=Fedorov |first7=Alexander N. |last8=Poirot |first8=Olivier |last9=Legendre |first9=Matthieu |last10=Santini |first10=Sébastien |last11=Abergel |first11=Chantal |last12=Claverie |first12=Jean-Michel |date=18 February 2023 |title=An Update on Eukaryotic Viruses Revived from Ancient Permafrost |journal=Viruses |language=en |volume=15 |issue=2 |pages=564 |doi=10.3390/v15020564 |doi-access=free |pmid=36851778 |pmc=9958942 |issn=1999-4915}}</ref><ref>{{Cite news |last=Luhn |first=Alec |date=2016-08-01 |title=Anthrax outbreak triggered by climate change kills boy in Arctic Circle |url=https://www.theguardian.com/world/2016/aug/01/anthrax-outbreak-climate-change-arctic-circle-russia |access-date=2024-01-22 |work=The Guardian |language=en-GB |issn=0261-3077}}</ref>

=== Artificial intelligence ===
Experts have raised concerns that advances in [[artificial intelligence]] could facilitate the design of particularly dangerous pathogens with pandemic potential. They recommended in 2024 that governments implement mandatory oversight and testing requirements.<ref>{{Cite magazine |last1=Pillay |first1=Tharin |last2=Booth |first2=Harry |date=2024-08-27 |title=AI Could One Day Engineer a Pandemic, Experts Warn |url=https://time.com/7014800/ai-pandemic-bioterrorism/ |access-date=2025-01-09 |magazine=TIME |language=en}}</ref>

== Economic consequences ==
In 2016, the commission on a Global Health Risk Framework for the Future estimated that pandemic disease events would cost the global economy over $6 trillion in the 21st century—over $60 billion per year.<ref>{{cite web|url=https://nam.edu/wp-content/uploads/2016/01/Neglected-Dimension-of-Global-Security.pdf|title=Global Health Risk Framework—The Neglected Dimension of Global Security: A Framework to Counter Infectious Disease Crises|date=16 January 2016|publisher=National Academy of Medicine|access-date=2 August 2016}}</ref> The same report recommended spending $4.5 billion annually on global prevention and response capabilities to reduce the threat posed by pandemic events, a figure that the World Bank Group raised to $13 billion in a 2019 report.<ref name=WBG2019>{{cite book |last=World Bank Group |date=September 2019 |title=Pandemic Preparedness Financing. Status Update |url=https://apps.who.int/gpmb/assets/thematic_papers/tr-4.pdf |archive-url=https://web.archive.org/web/20200301034712/https://apps.who.int/gpmb/assets/thematic_papers/tr-4.pdf |url-status=dead |archive-date=1 March 2020 |location=Washington |publisher=World Bank Group}}</ref> It has been suggested that such costs be paid from a tax on aviation rather than from, e.g., income taxes,<ref name=socarxiv2020>{{cite journal |vauthors=Pueyo S |date=12 May 2020 |title=Jevons' paradox and a tax on aviation to prevent the next pandemic |journal=SocArXiv |doi=10.31235/osf.io/vb5q3|s2cid=219809283 |url=http://osf.io/vb5q3/ }}</ref> given the crucial role of air traffic in transforming local epidemics into pandemics (being the only factor considered in state-of-the-art models of long-range disease transmission <ref name=natcomm2018>{{cite journal | vauthors = Wang L, Wu JT | title = Characterizing the dynamics underlying global spread of epidemics | journal = Nature Communications | volume = 9 | issue = 1 | pages = 218 | date = January 2018 | pmid = 29335536 | pmc = 5768765 | doi = 10.1038/s41467-017-02344-z | doi-access = free | bibcode = 2018NatCo...9..218W }}</ref>).

The COVID-19 pandemic is expected to have a profound [[COVID-19 recession|negative effect on the global economy]], potentially for years to come, with substantial drops in GDP accompanied by increases in unemployment noted around the world.<ref name="ACAIM-WACEM COVID-19 Consensus Paper"/> The slowdown of economic activity early in the COVID-19 pandemic had a profound effect on emissions of pollutants and greenhouse gases.<ref>{{cite journal |doi-access=free|doi=10.1038/s41558-020-0797-x|title=Temporary reduction in daily global CO<sub>2</sub> emissions during the COVID-19 forced confinement|year=2020| vauthors = Le Quéré C, Jackson RB, Jones MW, Smith AJ, Abernethy S, Andrew RM, De-Gol AJ, Willis DR, Shan Y, Canadell JG, Friedlingstein P | display-authors = 6 |journal=Nature Climate Change|volume=10|issue=7|pages=647–653|bibcode=2020NatCC..10..647L|hdl=10871/122774|hdl-access=free}}</ref><ref>{{cite web|url=https://www.nationalgeographic.com/science/2020/04/pollution-made-the-pandemic-worse-but-lockdowns-clean-the-sky/|archive-url=https://web.archive.org/web/20200409073134/https://www.nationalgeographic.com/science/2020/04/pollution-made-the-pandemic-worse-but-lockdowns-clean-the-sky/|url-status=dead|archive-date=9 April 2020|title=Pollution made COVID-19 worse. Now, lockdowns are clearing the air|date=8 April 2020|work=National Geographic Magazine|access-date=22 June 2020}}</ref><ref>{{cite journal | vauthors = Bauwens M, Compernolle S, Stavrakou T, Müller JF, van Gent J, Eskes H, Levelt PF, van der Veefkind JP, Vlietinck J, Yu H, Zehner C | display-authors = 6 | title = Impact of Coronavirus Outbreak on NO<sub>2</sub> Pollution Assessed Using TROPOMI and OMI Observations | journal = Geophysical Research Letters | volume = 47 | issue = 11 | pages = e2020GL087978 | date = June 2020 | pmid = 32836515 | pmc = 7261997 | doi = 10.1029/2020GL087978 | bibcode = 2020GeoRL..4787978B | doi-access = free }}</ref> Analysis of ice cores taken from the Swiss Alps has revealed a reduction in atmospheric lead pollution over a four-year period corresponding to the years 1349 to 1353 (when the Black Death was ravaging Europe), indicating a reduction in mining and economic activity generally.<ref>{{cite web|url=https://www.popsci.com/black-death-plague-air-pollution/|title=The Black Death helped reveal how long humans have polluted the planet|date=25 September 2017|work=Popular Science Magazine|access-date=22 June 2020}}</ref>

== See also ==
{{portal|border=no|Pandemics|Viruses|World}}
{{Div col|colwidth=30em}}
* [[Asian Flu]] of 1957
* [[Biological hazard]]
* [[Compartmental models in epidemiology]]
* [[Contagious disease]]
* [[Crowdmapping]]
* [[Disease X]]
* [[European Centre for Disease Prevention and Control]] (ECDC)
* [[Hong Kong Flu]] of 1968
* [[Immunization]]
* [[Index case]]
* [[Infectious disease#Disease|Mortality from infectious diseases]]
* [[List of pandemics and epidemics]]
* [[Mathematical modelling of infectious disease]]
* [[Medieval demography]]
* [[Pandemic fatigue]]
* [[Pandemic severity index]]
* [[Public health emergency of international concern]]
* [[Super-spreader]]
* [[Syndemic]]
* [[Tropical disease]]
* [[Timeline of global health]]
* [[Twindemic]]
* [[Vaccination]]
* [[WHO pandemic phases]]
{{div col end}}

== Notes ==
{{notelist}}

== References ==
{{Reflist}}

== Further reading ==
{{refbegin}}
* {{cite web|author=American Lung Association|author-link=American Lung Association|date=April 2007|title=Multidrug Resistant Tuberculosis Fact Sheet|url=http://www.lungusa.org/site/pp.aspx?c=dvLUK9O0E&b=35815|access-date=29 November 2007|url-status=dead|archive-url=https://web.archive.org/web/20061130122651/http://www.lungusa.org/site/pp.aspx?c=dvLUK9O0E&b=35815|archive-date=30 November 2006}}
* {{cite journal | vauthors = Bancroft EA | title = Antimicrobial resistance: it's not just for hospitals | journal = JAMA | volume = 298 | issue = 15 | pages = 1803–1804 | date = October 2007 | pmid = 17940239 | pmc = 2536104 | doi = 10.1001/jama.298.15.1803 }}
* {{cite journal | vauthors = [[Larry Brilliant|Brilliant L]], [[Mark Smolinski|Smolinski M]], [[Lisa Danzig|Danzig L]], [[W. Ian Lipkin|Lipkin WI]] | title =Inevitable Outbreaks: How to Stop an Age of Spillovers from Becoming an Age of Pandemics | journal = [[Foreign Affairs]] | volume = 102 | issue = 1 | date = January–February 2023 | pages = 126–130, 132–140 }}
* {{cite journal | vauthors = Brook T | title = Comparative pandemics: the Tudor–Stuart and Wanli–Chongzhen years of pestilence, 1567–1666 | journal = Journal of Global History | date = November 2020 | volume = 15 | issue = 3 | pages = 363–379 | doi = 10.1017/S174002282000025X | s2cid = 228979855 | doi-access = free }}
* {{cite journal | vauthors = Eisenberg M, Mordechai L | title = The Justinianic plague and global pandemics: The making of the plague concept. | journal = The American Historical Review | date = December 2020 | volume = 125 | issue = 5 | pages = 1632–1667 | doi = 10.1093/ahr/rhaa510 }}
* {{cite news | vauthors = Honigsbaum M  |date=18 October 2020 |title=How do pandemics end? In different ways, but it's never quick and never neat |work=The Guardian |url=https://www.theguardian.com/commentisfree/2020/oct/18/how-do-pandemics-end-in-different-ways-but-its-never-quick-and-never-neat |access-date=28 October 2020 |issn=0261-3077}}
* {{cite journal | vauthors = Larson E | title = Community factors in the development of antibiotic resistance | journal = Annual Review of Public Health | volume = 28 | pages = 435–447 | year = 2007 | pmid = 17094768 | doi = 10.1146/annurev.publhealth.28.021406.144020 | doi-access = free }}
* {{cite journal | vauthors = Lietaert Peerbolte BJ | date = September 2021 | title = The Book of Revelation: Plagues as Part of the Eschatological Human Condition | journal = [[Journal for the Study of the New Testament]] | publisher = [[SAGE Publications]] | volume = 44 | issue = 1 | pages = 75–92 | doi = 10.1177/0142064X211025496 | doi-access = free | issn = 1745-5294 | s2cid = 237332665 }}
* {{cite journal | vauthors = [[Maryn McKenna|McKenna N]] | title = Return of the Germs: For more than a century drugs and vaccines made astounding progress against infectious diseases. Now our best defenses may be social changes | journal = [[Scientific American]] | volume = 323 | issue = 3 | date = September 2020 | pages = 50–56 | quote = What might prevent or lessen [the] possibility [of a virus emerging and finding a favorable human host] is more prosperity more equally distributed – enough that villagers in South Asia need not trap and sell bats to supplement their incomes and that, low-wage workers in the U.S. need not go to work while ill because they have no sick leave }}
* {{cite book |last1=Ogilvie |first1=Sheilagh |title=Controlling Contagion: Epidemics and Institutions from the Black Death to Covid |date=2025 |publisher=Princeton University Press |location=Princeton |isbn=9780691255569}}
* {{cite magazine | vauthors = [[David Quammen|Quammen D]] | url = https://www.newyorker.com/magazine/2020/08/31/did-pangolins-start-the-coronavirus-pandemic | title = Did Pangolin Trafficking Cause the Coronavirus Pandemic | magazine = [[The New Yorker]] | date = 24 August 202 | pages = 26–31 (31) | quote = More field research is needed [...]. More sampling of wild animals. More scrutiny of genomes. More cognizance of the fact that animal infections can become human infections because humans are animals. We live in a world of viruses, and we have scarcely begun to understand this one. [ [[COVID-19]] }}
* {{cite web |url=https://ipbes.net/pandemics |title=Escaping the 'Era of Pandemics': Experts Warn Worse Crises to Come Options Offered to Reduce Risk |author=<!--Not stated-->|date=2020|publisher=[[Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services]]}}
{{refend}}

== External links ==
{{Commons category|Pandemics}}
{{Wiktionary}}
{{wikiquote}}
* [https://www.who.int/en/ WHO | World Health Organization]
* [http://news.bbc.co.uk/2/hi/health/4381924.stm Past pandemics that ravaged Europe]
* [https://www.cdc.gov/flu/pandemic-resources/ Pandemic Influenza] at [[Centers for Disease Control and Prevention|CDC]]
* [http://www.ecdc.europa.eu/ European Centre for Disease Prevention and Control]
* [https://www.youtube.com/user/TEDEducation?feature=watch TED-Education video] [https://www.youtube.com/watch?v=UG8YbNbdaco How pandemics spread].
{{Global catastrophic risks}}
{{History of medicine}}
{{Natural disasters}}
{{Disasters}}
{{Eradication of infectious disease}}
{{Epidemics}}
{{Concepts in infectious disease}}
{{Authority control}}

[[Category:Biological hazards]]
[[Category:Doomsday scenarios]]
[[Category:Economic problems]]
[[Category:Future problems]]
[[Category:Global health]]
[[Category:Health disasters]]
[[Category:Pandemics| ]]