April 15, 2020
Differential Susceptibility of Individuals and Communities to COVID-19
COVID-19 strikes with alarming inconsistency. Most recover quickly while others die. The disease devastates some communities and spares others. Understanding why and how COVID-19 preys on some and not others is essential to limiting its spread and mitigating its impact.
Prevention, averting, detecting, and restricting disease, is always better than even the most effective treatment. We need answers. Let’s go find them.
Although uneven in prevalence across communities, public health history shows that diseases typically spread by travel between population centers. Take a look at “The Ten Deadliest Epidemics Throughout History.” COVID-19 is closely tracking this historic pattern with a modern twist: science, intervention and technology can decrease morbidity and mortality.
Postulating genetic susceptibility in the article “COVID-19 Susceptibility: Why Do Some Become So Ill?” in MedPage Today, Dr. Mark Zucker observes the virulence of the Coronavirus is patient-dependent and might be genetically determined.  Italy has tragically experienced a fatality rate seven to ten times that of Germany and the United States.
Anecdotally, an ill-fated Italian-American family of eleven members experienced four COVID-19 deaths and two more critical care hospitalizations. Many variables, including random bad luck, could be causing these dreadful and variable statistics. Nonetheless, researching genetic susceptibility might reveal actionable insights.
In addition to genetic susceptibility, social determinants of health (SDOH) are key identifiers of vulnerable populations. The often-used warning in prevention literature, “Your ZIP code is more important than your genetic code,” suggests genetics are not primarily responsible for COVID-19 susceptibility.
In an important 2002 paper entitled “The Case for More Active Attention to Health Promotion,” Dr. Michael McGinnis defined the SDOH.  After years of research, he believed that genetics account for 30% of health and wellness, with the SDOH responsible for 70%.
That 70% further divides into four subcategories: 15% for social circumstances such as income and education; 5% for environment, 10% for medical care, and 40% for lifestyle choices. By addressing the 70% non-genetic factors for health and wellness, communities and individuals can improve their health status.
Individuals with chronic disease disproportionately die from COVID-19. In a March 2020 article, “Americans Unfit to Fight a Pandemic—Epidemics of Obesity, Sedentary Habits, and Chronic Stress Leave Nation With Poor Baseline Health” in Medpage Today, author Rami Bailony asserts that addressing personal or community SDOH will reduce pandemic mortality.
Bailony starts with a snapshot of shoppers in a national, big-box grocery store.  Packages of chips, candy bars, soda, frozen chicken wings, and other unhealthy foods overflow from the carts of overweight or obese purchasers. This creates a powerful visual for COVID-19’s top three co-morbidities: COPD; heart disease and diabetes.
COVID-19 kills by overwhelming the pulmonary system. Three prevalent lifestyle issues in American society compromise individuals’ pulmonary systems. They are obesity, tobacco use and sedentary behavior. Let’s examine each.
- Excess weight makes breathing more difficult. During the outbreak of H1N1 (i.e. bird flu) in 2009, 61% of people who died were obese with a body mass index (BMI) greater than 30.  Obesity is a risk factor for all pulmonary diseases.
- Cigarettes, e-cigarettes, and smokeless tobacco products stack up behind the counters of large chain pharmacies and convenience stores. Although the national smoking rate has decreased substantially, vaping has increased exponentially since 2007. This exposes a new population, largely young, to future pulmonary disease. Smoking doubles the chance of most infections and increases by 2.4 times the chance of severe illness—ICU admission, ventilator need and possible death.
- Sedentary behavior increases influenza-related hospitalization by up to 7%. Only 35% of people over age 65 are physically active. Moderate exercise increases immune function and strengthens the cardiovascular and pulmonary systems. A randomized study of people over age 50 enrolled in an exercise program had 35% fewer cold and flu episodes, and 47% fewer sick days.
Shocking anecdotal evidence indicates an intense connection between the worst of COVID-19 and ethnicity and poverty. “Early Data Shows African Americans Have Contracted and Died of Coronavirus at an Alarming Rate” argues that SDOH is the critical risk factor in in COVID-19’s spread and virulence. 
Authors Akilah Johnson and Talia Buford in ProPublica discuss that COVID-19 entered Milwaukee from a white, affluent suburb and subsequently erupted within the city’s low-income, black community. Clearly, economic stress, high population density, excess obesity, smoking rates, drug abuse, and lack of access to healthcare contribute to COVID-19’s rapid transmission, high prevalence, and increased mortality in marginalized communities.
As in Milwaukee, African American neighborhoods in Detroit and New Orleans, are disproportionately experiencing COVID-19’s lethal impact. Initially, governmental statistics on COVID-19 prevalence and mortality included age and location demographics, but not race. Beginning in April, Illinois and North Carolina began detailing COVID-19 cases by race. The evidence is incontrovertible. COVID-19 poses a grave threat to low-income communities afflicted with poor SDOH. The challenge is to increase preventive measures, as Chicago is doing, to limit disease spread to these vulnerable population.
Now and Forever
It is self-evident that a community of healthy, economically stable and happy people can withstand the onslaught of a pandemic better than a group of sick and sad people. Successful communities achieve longer life expectancy and a lower all-cause mortality by pursuing healthier lifestyles together. Improving SDOH may be the single best strategy for pandemic threat mitigation.
Preventing obesity, ceasing tobacco products, and boosting physical activity are all positive individual and community goals even in normal times. These are not normal times. COVID-19 should motivate America to embrace health and wellness broadly. Decreasing disease burden now increases our collective ability to repel the next pandemic.
- “The Ten Deadliest Epidemics Throughout History,” Health24 Infectious Diseases, September 2017.
- “COVID-19 Susceptibility: Why Do Some Become So Ill?” in MedPage Today Dr. Mark Zucker, April 2020.
- “The Case for More Active Attention to Health Promotion,” by J. MichaelMcGinnis, PamelaWilliams-Russo, and James R. Knickman, Health Affairs, March/April 2002.
- “Americans Unfit to Fight a Pandemic—Epidemics of Obesity, Sedentary Habits, and Chronic Stress Leave Nation With Poor Baseline Health,” in MedPage Today by Rami Bailony
- “A Novel risk Factor For a Novel Virus: Obesity and the 2009 Pandemic Influenza A (H1N1), Louie JK1, Acosta M, Samuel MC, Schechter R, Vugia DJ, Harriman K, Matyas BT; California Pandemic (H1N1) Working Group, Clinical Infectious Diseases, February 2011
- “Early Data Shows African Americans Have Contracted and Died of Coronavirus at an Alarming Rate,” by Akilah Johnson and Talia Buford in ProPublica, April 2020.