Understanding Drivers of COVID-19 Racial Disparities: A Population-Level Analysis of COVID-19 Testing among Black and White Populations.

BACKGROUND: Disparities in COVID-19 testing-the pandemic's most critical but limited resource-may be an important but modifiable driver of COVID-19 inequities. METHODS: We analyzed data from the Missouri State Department Health and Senior Services on all COVID-19 tests conducted in the St. Louis and Kansas City regions. We adapted a well-established tool for measuring inequity-the Lorenz curve-to compare COVID-19 testing rates per diagnosed case among Black and White populations. RESULTS: Between 3/14/2020 and 9/15/2020, 606,725 and 328,204 COVID-19 tests were conducted in the St. Louis and Kansas City regions, respectively. Over time, Black individuals consistently had approximately half the rate of testing per case compared to White individuals. In the early period (3/14/2020 to 6/15/2020), zip codes in the lowest quartile of testing rates accounted for only 12.1% and 8.8% of all tests in the St. Louis and Kansas City regions, respectively, even though they accounted for 25% of all cases each region. These zip codes had higher proportions of residents who were Black, without insurance, and with lower median incomes. These disparities were reduced but still persisted during later phases of the pandemic (6/16/2020 to 9/15/2020). Lastly, even within the same zip code, Black residents had lower rates of tests per case compared to White residents. CONCLUSIONS: Black populations had consistently lower COVID-19 testing rates per diagnosed case compared to White populations in two Missouri regions. Public health strategies should proactively focus on addressing equity gaps in COVID-19 testing to improve equity of the overall response.