Until a COVID-19 vaccine or preventive treatment is available, management of the COVID-19 pandemic will rely on a tried and true public health measure called contact tracing to keep you, your family, and your community safe. This method has been employed successfully for decades by the Illinois Department of Public Health and local health departments to prevent the spread of infectious diseases, such as vaccine preventable diseases, HIV/AIDS, and sexually transmitted infections. However, contact tracing for COVID-19 is different because it needs to be executed on a significantly larger scale, adapting to unique challenges of the virus, including its spread by people who do not have symptoms.

In general, contact tracing involves identifying people who have an infectious disease (cases) and people who they came in contact with (contacts) and working with them to stop the spread of the disease. This includes asking people with COVID-19 to isolate and asking their contacts to quarantine at home voluntarily. Quarantining allows contacts who were exposed to people who have an infectious disease to monitor themselves during the time period in which they could develop symptoms.

In Illinois, contact tracing is primarily carried out by local health department (LHD) staff.  However, in some situations, LHD staff cannot reach and monitor a case directly, such as cases in certain long term care facilities, correctional facilities, etc. For example, if a case lives in a nursing home, the LHD would work with facility staff to monitor the person and any of their close contacts and would not try to reach the person directly.  Although local health departments work closely with facility staff to minimize spread of COVID-19 within these types of facilities, these cases will not be reflected in the statistics presented below

Another scenario where a person may not be reflected in the statistics below is if someone is identified as a close contact to a case but the contact was themselves reported as a case within the past 90 days.  Current CDC contact tracing guidance specifies that asymptomatic contacts who were reported as a case in the past 90 days do not need to be quarantined

The information we collect helps public health officials understand how the virus is spreading in the community and affecting members of the community. Data are anonymized and analyzed at an aggregate level – no individuals would be traced back with the data shared

The metrics will be reported cumulatively, starting from August 1, 2020 to the Saturday of the previous week. On November 6, 2020, we will share the cumulative data from August 1, 2020 to October 24, 2020. Data will be refreshed every Friday. Data Methodology can be found here.

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Cases Data

Close Contacts Data

The metrics will be reported cumulatively, starting from August 1, 2020 to the Saturday of the previous week. On November 6, 2020, we will share the cumulative data from August 1, 2020 to October 24, 2020. Data will be refreshed every Friday. Data Methodology can be found below.

City of Chicago contact tracing data are collected in a separate data system. Data shown for the City of Chicago may not correspond directly with data presented for all other Illinois jurisdictions.

Data Methodology

Cases

A case is a person who meets either the confirmed or probable case definition for COVID-19.  Data presented on this page includes cases eligible to be monitored by local health departments directly and do not include cases known to be living in certain congregate settings (e.g., certain long term care facilities, correctional facilities, etc.) where the local health department cannot reach the case directly.

Cases Attempted

Contact Tracer has attempted to contact the person with COVID-19 via text, phone or email.

Cases Interviewed

Contact Tracer has successfully reached the person with COVID-19 and an interview was conducted.

Close Contact

For COVID-19, a close contact is defined as any individual who was within 6 feet of a reported case for at least 15 minutes starting from 2 days before illness onset (or, for asymptomatic case, 2 days prior to positive specimen collection) until the time the case is isolated. Data presented on this page includes close contacts eligible to monitored by local health departments directly and do not include close contacts known to be living in certain congregate settings (e.g., certain long term care facilities, correctional facilities, etc.) where the local health department cannot reach the close contact directly. Data presented on this page do not include close contacts who were reported as a case in the 90 days prior to their exposure to a case. ​ Additionally, if a person is reported as a close contact to multiple cases during the same time period, in the data presented on this page, the person is counted only once as a close contact and only one interview would be attempted for this person to discuss all identified exposures.  If a person is again identified as a close contact to a case after they have completed their initial quarantine period, they would be counted as a new close contact and an additional interview would be attempted.

Close Contacts Attempted

Contact Tracer has attempted to contact the person via text, phone or email.

Close Contacts Interviewed

Contact Tracer has successfully reached the person and an interview was conducted.