This is a single-site prospective study to evaluate the diagnostic performance of the investigational SeptiScan System for patients presenting to the Emergency Department with signs or suspicion of COVID-19 or other infectious respiratory diseases.

Inclusion Criteria:

Subjects meeting the following criteria may be eligible for participation in the study:

1. ≥ 18 years old or older

2. The first vital sign (any one of: blood pressure, temperature, pulse or respiratory rate) has been recorded in the medical record

3. A complete blood count has been ordered for which a blood sample has been collected within 4.5 hours since the first vital sign was recorded

4. Signs or suspicion of a respiratory infection, defined as:

   1. Subject designated for evaluation in the ED respiratory or pulmonary pod or similar location. OR
   2. An order placed for a respiratory viral panel. OR
   3. An order placed for a SARS-CoV-2 test. OR
   4. A subject self-reported as having tested positive for the SARS-CoV-2 test within the previous 7 days and returning with a related complaint.

Exclusion Criteria:

Subjects are excluded from study participation if they meet any of the following criteria:

a. Blood sample volume is < 300 ul; insufficient quantity for SeptiScan testing.

The study will enroll up to 300 participants from the emergency department at one clinical research site. Subjects who are suspected of having COVID-19 or other infectious respiratory diseases may be eligible for the study.