Illinois records highest single-day positivity rate since June 5

  • Sample instructor Kimberly Morgan of Chicago hands a test kit through a window to a test subject at the DuPage County COVID-19 testing site in Wheaton in June.

      Sample instructor Kimberly Morgan of Chicago hands a test kit through a window to a test subject at the DuPage County COVID-19 testing site in Wheaton in June. Mark Welsh | Staff Photographer, June 16

Updated 8/18/2020 4:10 PM

Illinois' rate of positive COVID-19 test results rose to 5.1% Tuesday, the highest since June 5.

The increase in the positivity rate, a key metric for assessing disease spread, came as state health officials reported 27 more Illinois residents had died from the disease.


Health officials announced 1,740 tests were positive for COVID-19 out of 34,175 tests given in one day.

That brings the state's death toll to 7,782, while 209,594 cases of COVID-19 have been diagnosed in Illinois residents since the outbreak began.

Tuesday's positivity rate was the first time a batch of test results had exceeded 5% positivity since June 5, when the day's positivity rate was 6.1%, according to Illinois Department of Public Health records.

The seven-day average infection rate for the state increased to 4.3% Tuesday, the highest level for that metric since June 10.

A higher positivity rate suggests higher transmission in the community and the likelihood that there are more people with the disease who haven't been tested yet, according to Johns Hopkins University public health experts.

Of Tuesday's new cases, 41.7% came from suburban Cook County, DuPage, Kane, Lake, McHenry and Will counties, according to IDPH figures. Chicago recorded 13.9% of Tuesday's new cases.

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The rest of the state was responsible for the remaining 44.4% of the new cases, with Madison and St. Clair counties in the Metro East region adjacent to St. Louis accounting for nearly 9% of the new cases. That region was put under more stringent restrictions that went into effect Tuesday after positivity rates exceeded 8% for five straight days. The region has also experienced an increase in the average positivity rate nine of the past 10 days.

By comparison, suburban Cook County's average positivity rate was 6.1% as of Sunday and the rate had increased three times over the 10-day period. In the region containing Lake and McHenry counties, the average positivity rate was 5.7% and had increased four times over the 10-day period.

The average positivity rate for the region with DuPage and Kane counties was at 4.8% on Sunday and had experienced increases on three days, but not since Aug. 10.

The region with Will and Kankakee counties is reporting an average positivity rate of 6.7%, and the rate has increased four times over the 10-day time frame, according to IDPH records.

Meanwhile, hospitalizations for COVID-19 have decreased statewide over the past two days. There are now 1,510 COVID-19 patients admitted to hospitals statewide for treatment, according to IDPH records. Of those hospitalized with the disease, 335 are in intensive care and 128 are on ventilators.

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