Mapping the Inequality of COVID-19 Household Exposure and Transmission Risk

Now that COVID-19 vaccines are becoming increasingly available — President Joe Biden has vowed to get another 100 million doses administered in his first 100 days in office — public health departments have more options for pandemic control.

But long-standing structural risk factors, including poverty, healthcare access barriers, and the legacy of residential segregation pose major challenges to curbing transmission.

Nearly 18 million people in the United States live in households with insufficient space to self-isolate (fewer rooms than people) and at least one essential worker. And more than half of those households — some 5.6% of the U.S. population — have a combined family income below 200% of the federal poverty line.

Then consider that nearly one-third of those households are multigenerational, many with elderly and children under one roof — and it becomes clear why they are at higher risk of contracting the COVID-19 virus, which has claimed more than 408,000 lives since last March.

Marissa Reitsma, a PhD student in Health Policy, used five years of the American Community Survey of the Census Bureau to map out areas with a high proportion of people at increased risk of being exposed to COVID-19 due to their occupation and housing characteristics. She and her colleagues published their findings in the Journal of General Internal Medicine.

The study found that people of color — 39% of the total population — account for 76% of those living in households at increased risk of exposure and transmission.

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The study maps one dimension of structural inequality closely linked to COVID-19 risks and health disparities, which can help to prioritize prevention efforts. Although much has been reported on the racial inequities of the pandemic, the study puts numbers behind those reports.

“This study provides hard numbers to what has been acknowledged in public discourse. It provides detailed estimates at a sub-county level that can be used to prioritize areas for outreach to encourage vaccine uptake and ensure coverage in the places that need it most,” Reitsma said. “We also hope that our study motivates equity-focused policies like support for safe self-isolation, cash assistance, and paid sick leave for low-income individuals that need to quarantine.”

They have posted their summary of the study with results, tables and maps.

Her co-authors are Joshua Salomon, a professor of medicine and senior fellow at the Freeman Spogli Institute for International Studies, and Jeremy Goldhaber-Fiebert, an associate professor of medicine. They are both faculty at Stanford Health Policy.

Goldhaber-Fiebert notes that while much has been reported about African American communities being hard hit by the pandemic, there has been much less detail reported on the Hispanic/Latino populations who reside in multigenerational, below-poverty-level households.

“Our study documents the experience of the Latino/Hispanic populations numbering 60 million nationwide. Outcomes for the Latino/Hispanic populations in California — numbering 15 million — have been worse than for non-Hispanic whites” he said.

Salomon adds that the results in the study may help to refine efforts to prioritize public health measures, including vaccination in order to direct them toward communities with the highest risk.

 “The vaccination rollout effort so far suggests that prioritizing interventions based on both individual characteristics and on geographic concentration of risk might help to achieve better outcomes in terms of reducing illness and mortality overall, and reducing disparities,” he said.

The work was supported by funding from the Centers for Disease Control and Prevention through the Council of State and Territorial Epidemiologists, and by the National Institute on Drug Abuse.