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Excerpted From: Nita Madhav, Ben Oppenheim, Mark Gallivan, Prime Mulembakani, Edward Rubin, and Nathan Wolfe, Chapter 17 Pandemics: Risks, Impacts, and Mitigation, Jamison DT, Gelband H, Horton S, et al., editors. Disease Control Priorities: Improving Health and Reducing Poverty. 3rd edition. Washington (DC): The International Bank for Reconstruction and Development / The World Bank; 2017 Nov 27. doi: 10.1596/978-1-4648-0527-1/pt5.ch17 (References Omitted) (Full Document)
Pandemics can cause sudden, widespread morbidity and mortality as well as social, political, and economic disruption. The world has endured several notable pandemics, including the Black Death, Spanish flu, and human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) (table 17.1).
Because the definition of pandemic primarily is geographic, it groups together multiple, distinct types of events and public health threats, all of which have their own severity, frequency, and other disease characteristics. Each type of event requires its own optimal preparedness and response strategy; however this chapter also discusses common prerequisites for effective response. The variety of pandemic threats is driven by the great diversity of pathogens and their interaction with humans. Pathogens vary across multiple dimensions, including the mechanism and dynamics of disease transmission, severity, and differentiability of associated morbidities. These and other factors determine whether cases will be identified and contained rapidly or whether an outbreak will spread . As a result, pathogens with pandemic potential also vary widely in the scale of their potential health, economic, and sociopolitical impacts as well as the resources, capacities, and strategies required for mitigation.
One must distinguish between several broad categories of pandemic threats. At one extreme are pathogens that have high potential to cause truly global, severe pandemics. This group includes pandemic influenza viruses. These pathogens transmit efficiently between humans, have sufficiently long asymptomatic infectious periods to facilitate the undetected movement of infected persons, and have symptomatic profiles that present challenges for differential diagnosis (particularly in the early periods of infection). A second group of pathogens presents a moderate global threat. These agents (for example, Nipah virus and H5N1 and H7N9 influenzas) have not demonstrated sustained human-to-human transmission but could become transmitted more efficiently as a result of mutations and adaptation. A third group of pathogens (for example, Ebola, Marburg, Lassa) has the potential to cause regional or interregional epidemics, but the risk of a truly global pandemic is limited because of the slow pace of transmission or high probability of detection and containment.
Among all known pandemic pathogens, influenza poses the principal threat because of its potential severity and semiregular occurrence since at least the 16th century. The infamous 1918 influenza pandemic killed an estimated 20 million to 100 million persons globally, with few countries spared. Its severity reflects in part the limited health technologies of the period, when no antibiotics, antivirals, or vaccines were available to reduce transmission or mortality.
During the 1918 pandemic, populations experienced significantly higher mortality rates in LMICs than in HICs, likely as a result of higher levels of malnutrition and comorbid conditions, insufficient access to supportive medical care, and higher rates of disease transmission. The mortality disparity between HICs and LMICs likely would be even greater today for a similarly severe event, because LMICs have disproportionately lower medical capacity, less access to modern medical interventions, and higher interconnectivity between population centers.
|Starting year||Event||Geographic extent||Estimated direct morbidity or mortality||Estimated economic, social, or political impact|
|1347||Bubonic plague (Black Death) pandemic||Eurasia||30–50 percent mortality of the European population (DeWitte 2014)||Likely hastened end of the feudal system in Europe (Platt 2014)|
|Early 1500s||Introduction of smallpox||Americas||More than 50 percent mortality in some communities (Jones 2006)||Destroyed native societies, facilitating the hegemony of European countries (Diamond 2009)|
|1881||Fifth cholera pandemic||Global||More than 1.5 million deaths (9.7 per 10,000 persons) (Chisholm 1911)||Sparked attacks on Russian tsarist government and medical officials (Frieden 1977)|
|1918||Spanish flu influenza pandemic||Global||20 million–100 million deaths (111–555 deaths per 10,000 persons) (Johnson and Mueller 2002)||GDP loss of 3 percent in Australia, 15 percent in Canada, 17 percent in the United Kingdom, 11 percent in the United States (McKibbin and Sidorenko 2006)|
|1957||Asian flu influenza pandemic||Global||0.7 million–1.5 million deaths (2.4–5.1 deaths per 10,000 persons) (Viboud and others 2016)||GDP loss of 3 percent in Canada, Japan, the United Kingdom, and the United States (McKibbin and Sidorenko 2006)|
|1968||Hong Kong flu influenza pandemic||Global||1 million deaths (2.8 deaths per 10,000 persons) (Mathews and others 2009)||US$23 billion–US$26 billion direct and indirect costs in the United States (Kavet 1977)|
|1981||HIV/AIDS pandemic||Global||More than 70 million infections, 36.7 million deaths (WHO Global Health Observatory data, http://www.who.int/gho/hiv/en/)||2–4 percent annual loss of GDP growth in Africa (Dixon, McDonald, and Roberts 2001)a|
|2003||SARS pandemic||4 continents, 37 countries||8,098 possible cases, 744 deaths (Wang and Jolly 2004)||GDP loss of US$4 billion in Hong Kong SAR, China; US$3 billion–US$6 billion in Canada; and US$5 billion in Singapore (Keogh-Brown and Smith 2008)|
|2009||Swine flu influenza pandemic||Global||151,700–575,500 deaths (0.2–0.8 per 10,000 persons) (Dawood and others 2012)||GDP loss of US$1 billion in the Republic of Korea (Kim, Yoon, and Oh 2013)|
|2012||MERS epidemic||22 countries||1,879 symptomatic cases, 659 deaths (Arabi and others 2017)||US$2 billion loss in the Republic of Korea, triggering US$14 billion in government stimulus spending (Jun 2015; Park and Kim 2015)|
|2013b||West Africa Ebola virus disease epidemic||10 countries||28,646 cases, 11,323 deaths (WHO 2016a)||US$2 billion loss in Guinea, Liberia, and Sierra Leone (World Bank 2014)|
|2015||Zika virus pandemic||76 countries||2,656 reported cases of microcephaly or central nervous system malformation (WHO 2017)||US$7 billion–US$18 billion loss in Latin America and the Caribbean (UNDP 2017)|
Note: List of events is illustrative rather than exhaustive. All U.S. dollar amounts are rounded to nearest billion. GDP = gross domestic product; HIV/AIDS = human immunodeficiency virus/acquired immunodeficiency syndrome; MERS = Middle East respiratory syndrome; SARS = severe acute respiratory syndrome.
a Studies of the effects of HIV/AIDS on per capita gross national product have found smaller effects.
b The West Africa Ebola virus outbreak occurred from 2013 to 2016, but the peak and international response efforts began in 2014.