Study population and setting
U.S. county-level data (n=3,412 counties) on COVID-19 diagnosis and deaths through mid-April 2020 were linked to county-level data on demographics (age group, race, unemployment, urbanicity), environment (urbanicity, air quality, social distancing), and healthcare access (insurance) from various sources from 2014-2020, including the U.S. Census Bureau, the Centers for Disease Control, and Unacast. Bayesian hierarchical models adjusting for time since first case were used to estimate rate ratios for counties with a higher vs. lower proportion of Black residents (as compared to the national average), adjusting for county-level characteristics. Population attributable fractions were estimated for all, disproportionately Black, and non-disproportionately Black counties.
Summary of Main Findings
By April 13, 2020, 52% of diagnoses (n= 283,750) and 58% of deaths (n=12,748) were reported in communities where 13% or more of residents were Black (higher proportion). After adjustment for county-level characteristics, counties with a higher proportion of people who were Black remained associated with higher rates of diagnosis (ratio = 1.24; 95%CI 1.17-1.33) and death (ratio = 1.18; 95%CI 1.00 – 1.40). For diagnosis, significantly higher rates were observed across the urbanicity spectrum; associations with death were only significant among small metropolitan and non-core areas. Population attributable fractions estimated excess deaths associated with occupancy crowding (280,112) and lack of health insurance (126,985).
The study analyzed data from nearly all US counties, included a wide range of predictors associated with infection and severe COVID19 prognosis, and used appropriate regression methods for small area estimation.
As an ecological study, it cannot link data on race, diagnosis, death, or confounders at the individual level. As such, measures of disparate COVID-19 diagnosis or death, and their causes, were not estimated by this study. The reported community-level associations may be underestimated due to barriers to diagnosis and treatment of COVID19 complications.
This study confirms that, nationally, higher rates of COVID-19 infection and death were found among communities of color even with adjustment for additional community factors.