The wording's pretty vague, but from what I can gather the general idea is that redlined communities are at much greater risk of mass COVID-19 infections as a result of them being too economically disadvantaged to afford many amenities for preventing, detecting, and treating the disease. Redlining itself is heavily biased against nonwhite populations, especially black ones, which is where white supremacy factors in (as redlining is in execution a sort of "soft segregation").