Pandemic risk factors

Pandemic risk, as noted, is driven by the combined effects of spark risk and spread risk. The foci of both risk factors often overlap, especially in some LMICs (such as in Central and West Africa and Southeast Asia), making these areas particularly vulnerable to pandemics and their negative consequences.

Spark Risk

A zoonotic spark could arise from the introduction of a pathogen from either domesticated animals or wildlife. Zoonoses from domesticated animals are concentrated in areas with dense livestock production systems, including areas of China, India, Japan, the United States, and Western Europe. Key drivers for spark risk from domesticated animals include intensive and extensive farming and livestock production systems and live animal markets, as well as the potential for contact between livestock and wildlife reservoirs (Gilbert and others 2014Jones and others 2008).

Wildlife zoonosis risk is distributed far more broadly, with foci in China, India, West and Central Africa, and the Amazon Basin (Jones and others 2008). Risk drivers include behavioral factors (such as bushmeat hunting and use of animal-based traditional medicines), natural resource extraction (such as sylviculture and logging), the extension of roads into wildlife habitats, and environmental factors (including the degree and distribution of animal diversity) (Wolfe and others 2005).

Spread Risk

After a spark or importation, the risk that a pathogen will spread within a population is influenced by pathogen-specific factors (including genetic adaptation and mode of transmission) and human population-level factors (such as the density of the population and the susceptibility to infection; patterns of movement driven by travel, trade, and migration; and speed and effectiveness of public health surveillance and response measures) (Sands and others 2016).

Dense concentrations of population, especially in urban centers harboring overcrowded informal settlements, can act as foci for disease transmission and accelerate the spread of pathogens (Neiderud 2015). Moreover, social inequality, poverty, and their environmental correlates can increase individual susceptibility to infection significantly (Farmer 1996). Comorbidities, malnutrition, and caloric deficits weaken an individual’s immune system, while environmental factors such as lack of clean water and adequate sanitation amplify transmission rates and increase morbidity and mortality (Toole and Waldman 1990). Collectively, all these factors suggest that marginalized populations, including refugees and people living in urban slums and informal settlements, likely face elevated risks of morbidity and mortality during a pandemic.

A country’s expected ability to curtail pandemic spread can be expressed using a preparedness index developed by Oppenheim and others (2017). The index illustrates global variation in institutional readiness to detect and respond to a large-scale outbreak of infectious disease. It draws on the IHR core capacity metrics and other publicly accessible cross-national indicators. However, it diverges from the IHR metrics in its breadth and focus on measuring underlying and enabling institutional, infrastructural, and financial capacities such as the following (Oppenheim and others 2017):

  • Public health infrastructure capable of identifying, tracing, managing, and treating cases
  • Adequate physical and communications infrastructure to channel information and resources
  • Fundamental bureaucratic and public management capacities
  • Capacity to mobilize financial resources to pay for disease response and weather the economic shock of the outbreak
  • Ability to undertake effective risk communications.

Well-prepared countries have effective public institutions, strong economies, and adequate investment in the health sector. They have built specific competencies critical to detecting and managing disease outbreaks, including surveillance, mass vaccination, and risk communications. Poorly prepared countries may suffer from political instability, weak public administration, inadequate resources for public health, and gaps in fundamental outbreak detection and response systems.

Map 17.1 presents the global distribution of epidemic preparedness, with countries grouped into quintiles. A geographic analysis of preparedness shows that some areas of high spark risk also are the least prepared. Geographic areas with high spark risk from domesticated animals (including China, North America, and Western Europe) have relatively higher levels of preparedness, although China lags behind its counterparts. However, geographic areas with high spark risk from wildlife species (including Central and West Africa) have some of the lowest preparedness scores globally, indicating a potentially dangerous overlap of spark risk and spread risk.