Illinois: Viral (PCR) Tests

Total number of completed PCR tests (or specimens tested) that return positive as reported by the state or territory. If we discover that a jurisdiction is including antigen tests in this metric, we will annotate that state or territory’s data accordingly.

Total number of unique people tested at least once via PCR testing, as reported by the state or territory. The count for this metric is incremented up only the first time an individual person is tested and their result is reported. Future tests of the same person will not be added to this count.

In the case where the state only provides negative cases, this field is calculated as the summation of people who tested positive (“Positive Cases (People”) and the number of people who tested negative (“Negative (People or Cases)”). If we discover that a jurisdiction is including antigen tests in this metric, we will annotate that state or territory’s data accordingly.

Total number of PCR tests (or specimens tested) as reported by the state or territory. The count for this metric is incremented up each time a specimen is tested and the result is reported. If we discover that a jurisdiction is including antigen tests in this metric, we will annotate that state or territory’s data accordingly. For states with ambiguous annotations, we have assigned their total tests to this category; these states and territories are identified in the new API field covidTrackingProjectPreferredTotalTestUnits as having “Unclear units.”

Total number of people tested per day via PCR testing as reported by the state or territory. The count for this metric is incremented up by one for each day on which an individual person is tested, no matter how many specimens are collected from that person on that day. If an individual person is tested twice a day on three different days, this count will increment up by three. If we discover that a jurisdiction is including antigen tests in this metric, we will annotate that state or territory’s data accordingly.

At the national level, this metric is a summary statistic which, because of the variation in test reporting methods, is at best an estimate of US viral (PCR) testing. Some states/territories report tests in units of test encounters, some report tests in units of specimens, and some report tests in units of unique people. Moreover, some jurisdictions include antigen tests in their total test counts without reporting a separate total of viral (PCR) tests. Therefore, this value is an aggregate calculation of heterogeneous figures. Please consult each state or territory’s individual data page to see whether that jurisdiction lumps antigen and PCR tests together and to see what units that jurisdiction uses for test reporting.

In most states, the totalTestResults field is currently computed by adding positive and negative values because, historically, some states do not report totals, and to work around different reporting cadences for cases and tests. In Colorado, Delaware, the District of Columbia, Florida, Hawaii, Minnesota, Nevada, New York, North Dakota, Pennsylvania, Rhode Island, Virginia, Washington, and Wisconsin, where reliable testing encounters figures are available with a complete time series, we directly report those figures in this field. In Alaska, America Samoa, Arizona, Arkansas, California, Connecticut, Georgia, Illinois, Indiana, Kentucky, Maine, Maryland, Massachusetts, Michigan, Missouri, Montana, Nebraska, New Hampshire, New Mexico, North Carolina, Ohio, Oregon, South Dakota, Tennessee, Texas, Utah, Vermont, West Virginia, and Wyoming, where reliable specimens figures are available with a complete time series, we directly report those figures in this field. In Alabama and Idaho where reliable unique people figures are available with a complete time series, we directly report those figures in this field. We are in the process of switching all states over to use directly reported total figures, using a policy of preferring testing encounters, specimens, and people, in that order.