The famous discovery of the origin of a cholera outbreak in a London water pump in 1854 by Dr. John Snow—often regarded as the birth of both the modern city and the field of epidemiology—was achieved through a map. Before 1854, this area of London had no sewer system and was steeped in muck and filth. Cholera previously killed over 14,000 people during outbreaks in 1832 and 1849, but the cause of the disease was yet unknown. Dr. Snow mapped the deaths from cholera at the household level and then eventually came upon the idea of mapping all of the area’s water pumps. The resulting overlap map showed a clear correlation between the one water pump and deaths. By removing the water pump handle, the outbreak was contained and stopped.
Given that early success in associating health and place, it’s surprising how little we have applied geography in shaping either our knowledge of what determines health, such as nearness to pollutants or access to care, or our strategies for achieving it, such as equitable allocation of resources or geographically targeted and tailored interventions. This has arguably been a significant mistake in analysis. But it is certainly a mistake in strategy.
Place not only helps us understand our full health context, but also shows us where and how to intervene.”
The classic “epidemiologic triad” consists of (1) agent of disease, (2) a susceptible host, and (3) the environment. Medical science has made great advances in identifying and addressing the first two—from antibiotics to genetics to advances in medical technology. We have made less progress on the third—a contextual cornucopia that includes the built environment, the social determinants of health, and local ambient conditions.
What we have learned is that 80% of our health outcomes are context-driven: physical environment (10%); health behaviors (30%); and social and economic factors (40%). Only the remaining 20% is determined by a person’s genome and microbiome (the symbiotic organisms—including billions of bacteria and other microbes—that make up an individual human being) and the clinical care they receive.
These first three factors are known collectively as the “exposome,” defined as the measure of all the exposures of an individual in a lifetime. A person’s exposure begins before birth and includes inputs from environmental and occupational sources, such as climate, metals and plastics, ozone, pollution, tobacco, pesticides, infection, stress, and socioeconomic factors.
What we have come to see is that the best way to organize and analyze that exposomic complexity is through location.
Even in normal times, your ZIP code can be as important to your health outcomes as either your genetic code or your tax code. Average life expectancy, the ultimate measure of population health, can vary by 20-30 years from place to place. Now multiply that by an order of magnitude during a pandemic. As the Centers for Disease Control and Prevention puts it, “Both the who and the when of disease are relative to and often dependent on the where.”
Fortunately, we now have the means to understand that “where.” Through an emerging geospatial mindset and the new tools of location intelligence, enhanced by artificial intelligence, we can now analyze environmental and societal complexity in their impact on our health.
The “where” turns out to be the best lens for determining how to fight disease and produce public health. Place not only helps us understand our full health context but also shows us where and how to intervene.
Take the current COVID-19 pandemic.
- Mapping the epidemic: The sophisticated mapping capacities developed during the West Nile, SARS, Ebola, and Zika epidemics are used today to track measles, polio, and other infectious diseases—and have proven invaluable during COVID-19. The current exemplar of this emerging capability is the globally famous COVID dashboards. There are dozens, with the most prominent being those of the World Health Organization and Johns Hopkins University.
- Contact tracing: Advanced location intelligence helps leaders detect patterns in real time, spotting anomalies, gaining insights, and quelling the spread of the disease by understanding linkages beyond cases and contacts to include the places people have visited.
- Protecting the most vulnerable: Smart maps that display U.S. Census Bureau data about age and income, layered with information about senior living facilities, homeless encampments, hospitals, and clinics, have become vital. With simple spatial analytics, this layered information can create localized risk scores that are highly actionable.
Smart maps and dashboards are also helping with prediction and planning for how many people will need hospitalization; addressing food shortages; and enabling companies to adapt indoor workspaces for when employees return to work.
These location intelligence-based approaches allow us to move beyond personalized medicine to precision medicine, and beyond precision medicine to precision public health.
In the end, the pandemic has elevated the awareness of the value of location intelligence across the globe. We are beginning to see, firsthand, the impact of applied geography in shaping our knowledge about what determines health in a pandemic. And certainly, we have seen strategic applications of geography to support response efforts. We cannot “un-know” these lessons. It’s time to broaden our use of location intelligence across all sectors of health to continue to better prepare and respond to the challenges that place imposes on our bodies.
The coronavirus pandemic reminds us that we’re all in the same boat. As David Wolman put it in Wired, “the very concept of elsewhere is a fiction. . . . Where matters—absolutely. But it’s also true that we all live right here. Together.”
Still, in another way, the virus is reinforcing the centrality of microlocation. The unique combinations of societal, environmental, and cultural characteristics of a given city, neighborhood, or block are decisive in determining the virus’s impact on those communities. Just as important, they show us where and what to do about it.
Dr. Este Geraghty is a physician and the chief medical officer for Esri, a global technology and data science company.