Each test result, positive and negative, is entered into the Electronic Laboratory Reporting (ELR) system by state, commercial or hospital laboratories. The total number of tests and the results are reported daily to IDPH.
Positivity rate is the percentage of tests that are positive for COVID-19.
Case rate is the number of positive cases per 100,000 people in a certain population of interest. 2018 population estimates from the Census Bureau are used in the calculation.
Race/ethnicity is self-identified by the patient at the time of testing and is missing for approximately 50% of tests.