On September 1, 2021, IDPH adopted the updated 2021 COVID-19 national case definition. As part of this case definition, IDPH began including in its total case counts individuals who previously were reported as a confirmed or probable case, but have become infected again. Therefore, total case counts no longer represent unique individuals as those individuals meeting the new criteria** may be counted more than once. These changes will apply only to cases with new positive test results on or after September 1, 2021.
**Criteria to Distinguish a New Case from an Existing Case – New confirmed or probable cases will be enumerated if SARS-CoV-2 sequencing results from a new positive specimen and a positive specimen from the most recent previous case demonstrate a different lineage OR if the person was most recently counted as a confirmed or probable case with onset date (if available) or first positive specimen collection date for that classification more than 90 days prior. The entire national case definition can be found at: https://ndc.services.cdc.gov/case-definitions/coronavirus-disease-2019-2021/
*Total molecular and antigen tests performed and reported electronically for testing of COVID-19 at IDPH, commercial or hospital laboratories. All numbers displayed are provisional and will change.