If this issue were simply a case of economics then this would only be apparent in the US due to citizen's health insurance being tied to employment, but the fact that it is occurring also in the UK, a country with a free national health system, makes it clear other issues are at play here. Health vulnerabilities are not as simple as pure economics, although many of the contributing issues are linked to poverty in some way also; racial inequalities in health, education, housing, and employment exist in both the UK and the US. These are divisions of poverty, there are racial divides of in many aspects of life that leave minorities more at risk of catching contagious diseases and more at risk of having a fatal reaction to a contagious disease, it is important not to hide these issues all behind poverty as racial inequality goes far deeper.
All of these factors open up scenarios that lead to ethnic minorities being more likely to be exposed to the virus, being more likely to work insecure, low-paid work, be unemployed, or to live in overcrowded housing. In addition to a statistical propensity to have underlying health conditions, which is itself a complex mixture of poverty, a failure of education, and inadequate preventative healthcare, leaving racial minorities more vulnerable to COVID-19 on multiple levels. Poverty is just part of the picture here, the inequality that ethnic minorities face in the UK and America is much more multifaceted than a simple matter of wealth.