Just looking at the map and knowing about population distributions in DuPage County, there are both more cases and higher rates of cases in certain communities: Addison, West Chicago, Glendale Heights, Carol Stream, and Bensenville. These are communities with more diverse populations.
Data from the dashboard also look at rates by ethnicity and race:
The case rate for Latinos is 5.5 times that of whites though the Latino mortality rate is slightly lower. The case rate for Blacks is 2.1 times that of whites and 1.7 times that of Asians and Black mortality rates are higher at similar amounts. Further data breaks this down by ethnicity and age and race and age with case rates being much higher for Latinos and Blacks among those 60 and older (and rates are higher at all adult age groups).
Put these together and COVID-19’s impact on DuPage County depends on race, ethnicity, and location. This also probably means COVID-19 has some connection to social class since DuPage County communities, like many metropolitan regions, have different levels of income and housing costs.