Illinois COVID-19 Testing Needs

A medical professional administers a COVID-19 nasal swab test.

Previous research estimated the actual number of COVID-19 cases in Chicago.  Since then, seven additional deaths occurred, totaling 12 deaths, with a total of 1,285 confirmed cases in Illinois.

While the infection rapidly spreads throughout the state, the testing capacity is still lagging, which poses great danger.  Without a broader testing available, it will be very difficult to effectively implement isolation and to prepare the state’s healthcare system.  As of Monday, March 23, Illinois performed a total of 9,868 tests starting March 4, an average of 493 tests per day.  Of these tests, 1,285 tests were positive and 8,583 were negative, or a 13 percent positive rate.  Fortunately, testing capacity seems to be increasing.  Since March 20, Illinois has been testing more than 1,500 people per day.  However, testing is not readily available to the point of identifying potentially widespread spread of infection.

In this report, we estimate the number of tests that the State of Illinois will need to perform in order to be able to catch up to the number of estimated undetected infection cases.  As we describe in the previous report, we estimate the number of undetected COVID-19 cases for the whole of Illinois, using the same parameters that we utilized for Chicago estimates: mortality rate at 1%, with 20 days of infection to death, and 6 days of doubling time.

Using the number of deaths (n=12) in Illinois, we estimate the total number of COVID-19 cases in Illinois on March 23 is 12,095, while the total number of confirmed cases for Illinois is 1,285.  With the six-day double time, the number will increase to more than 24,000 cases by March 29.  If the detection rate stays at 13 percent, we will need to implement about 21,000 tests per day for the next six days to capture the estimated positive cases.

Data sources used include the COVID Tracking Project and Illinois data from both the Johns Hopkins Github and the Illinois Department of Public Health.

About the authors

Jiehuan Sun, PhD, assistant professor of biostatistics, is working with health policy researchers at the School of Public Health to use biostatistics to estimate the actual number of COVID-19 cases in the state of Illinois.  The analysis is being used in mapping efforts at the School of Public Health.

Sage Kim, PhD, associate professor of health policy and administration, is monitoring how prisons across states are planning for COVID-19 and communicating results through an incarcerated population health national listserve.  With students in her social vulnerability course at the School of Public Health, she is mapping confirmed cases and deaths from COVID-19 in Chicago and Illinois.  She is also applying a social vulnerability index to estimate COVID-19 risks for populations.

Timothy Jostrand is an MPH in Health Policy and Administration student at the UIC School of Public Health.

Updated Illinois confirmed cases, deaths and tests performed

Date Confirmed Estimated Deaths Cumulative Tests Daily Tests Cumulative Negative
1/22/20 0 11 0 0 0 0
1/23/20 0 12 0 0 0 0
1/24/20 1 13 0 0 0 0
1/25/20 1 15 0 0 0 0
1/26/20 1 17 0 0 0 0
1/27/20 1 19 0 0 0 0
1/30/20 1 27 0 0 0 0
1/31/20 2 30 0 0 0 0
2/1/20 2 33 0 0 0 0
2/2/20 2 38 0 0 0 0
2/3/20 2 42 0 0 0 0
2/4/20 2 47 0 0 0 0
2/5/20 2 53 0 0 0 0
2/6/20 2 60 0 0 0 0
2/7/20 2 67 0 0 0 0
2/8/20 2 75 0 0 0 0
2/9/20 2 84 0 0 0 0
2/10/20 2 94 0 0 0 0
2/11/20 2 106 0 0 0 0
2/12/20 2 119 0 0 0 0
2/13/20 2 134 0 0 0 0
2/14/20 2 150 0 0 0 0
2/15/20 2 168 0 0 0 0
2/16/20 2 189 0 0 0 0
2/17/20 2 212 0 0 0 0
2/18/20 2 238 0 0 0 0
2/19/20 2 267 0 0 0 0
2/20/20 2 300 0 0 0 0
2/21/20 2 337 0 0 0 0
2/22/20 2 378 0 0 0 0
2/23/20 2 424 0 0 0 0
2/24/20 2 476 0 0 0 0
2/25/20 2 535 0 0 0 0
2/26/20 2 600 0 0 0 0
2/27/20 2 673 0 0 0 0
2/28/20 2 756 0 0 0 0
2/29/20 2 849 0 0 0 0
3/1/20 3 952 0 0 0 0
3/2/20 4 1,069 0 0 0 0
3/3/20 4 1,200 0 0 0 0
3/4/20 4 1,347 0 155 155 124
3/5/20 5 1,512 0 197 42 165
3/6/20 5 1,697 0 220 23 180
3/7/20 8 1,905 0 241 21 191
3/8/20 11 2,138 0 241 0 191
3/9/20 15 2,400 0 242 1 191
3/10/20 19 2,694 0 326 84 244
3/11/20 29 3,024 0 326 0 244
3/12/20 39 3,394 0 367 41 266
3/13/20 46 3,810 0 418 51 294
3/14/20 64 4,276 0 444 26 316
3/15/20 102 4,800 0 708 264 449
3/16/20 105 5,388 0 1,025 317 932
3/17/20 161 6,048 1 1,500 475 1,340
3/18/20 288 6,788 1 2,052 522 1,763
3/19/20 422 7,260 4 3,151 1,099 2,725
3/20/20 585 8,553 5 4,286 1,135 3,696
3/21/20 753 9,600 6 6,247 1,961 5,488
3/22/20 1,049 10,776 9 8,329 2,082 7,271
3/23/20 1,285 12,095 12 9,868 1,539 8,583

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