Social inequality, chronic disease and COVID-19: county-level analysis in the United States
Islam N., LACEY B., Shabnam S., Erzurumluoglu AM., DAMBHA-MILLER H., Chowell G., Kawachi I., Marmot M.
Background: Given the effect of chronic diseases on risk of severe COVID-19 infection, the present pandemic may have a particularly profound impact on socially disadvantaged counties. Methods: Counties in the USA were categorised into five groups by level of social vulnerability, using the Social Vulnerability Index (a widely-used measure of social disadvantage) developed by the US Centers for Disease Control. The incidence and mortality from COVID-19, and the prevalence of major chronic conditions were calculated relative to the least vulnerable quintile using Poisson regression models. Results: Among 3141 counties, there were 5,010,496 cases and 161,058 deaths from COVID-19 by August 10, 2020. Relative to the least vulnerable quintile, counties in the most vulnerable quintile had twice the rates of COVID-19 cases and deaths (rate ratios 2.11 [95%CI: 1.97-2.26] and 2.42 [2.22-2.64], respectively). Similarly, the prevalence of major chronic conditions was 24-40% higher in the most vulnerable counties. Geographic clustering of counties with high COVID-19 mortality, high chronic disease prevalence and high social vulnerability was found, especially in southern USA. Conclusion: Some counties are experiencing a confluence of epidemics from COVID-19 and chronic diseases in the context of social disadvantage. Such counties are likely to require enhanced public health and social support.