Symphony IL-6 is a device that quantitates human IL-6 by fluorescence enzyme immunoassay (FEIA) from whole-blood specimens. Use of Symphony IL- 6 removes the need for plasma separation before testing. Symphony IL-6 comprises two components, the Symphony Fluorescence Immunoanalyzer and the Symphony IL-6 Cartridge. Whole blood is added to the cartridge and then up to six cartridges can be inserted into the immunoanalyzer. After 20 minutes a readout and printout are given with a quantitative IL-6 concentration. The used cartridges are fully enclosed and can be easily disposed of in general hospital bio-waste. Given the nature of this device and its portability, there is potential for future deployment as a point-of-care (POC) device.

This study is to establish an interleukin-6 (IL-6) cutoff value using the Symphony IL-6 test for patients at high risk of severe sepsis caused by a COVID-19 infection.

Inclusion Criteria:

• Whole-blood specimen collected in K2 EDTA anticoagulant tubes
• Subject is considered to have severe or critical illness per below:

Severe Illness

1. SpO2 < 94% on room air at sea level;
2. Ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) < 300 mmHg;
3. Respiratory frequency > 30 breaths/min;
4. Or lung infiltrates >50% Critical Illness

a) Respiratory failure; b) Septic shock; c) And/or multiple organ dysfunction d) At least one criterion of severe illness

• Subject confirmed to be COVID-19 positive by an EUA RT-PCR test
• Subject is 18+ years of age
• Minimum volume of 100µL for Symphony IL-6 testing
• Specimen is available for testing within 12 hours from collection

Exclusion Criteria:

• Subject is receiving an anti-IL-6 treatment
• Subject is receiving corticosteroids
• Hemolyzed specimens

This study will test 96 remnant, whole-blood specimens collected as baseline samples from confirmed COVID-19 patients at the University of Texas Southwestern Medical Center. Subjects will be symptomatic and have been confirmed by an emergency use authorized (EUA) real-time polymerase chain reaction (RT-PCR) test to be COVID-19 positive. The whole-blood specimens will have been submitted to the local laboratory for routine testing.