Inclusion Criteria:  Signed informed consent (IC) within 4 days of COVID-19 test. Age 18 or older COVID-19 test  Group 1: negative COVID-19 test Group 2: positive COVID-19 test with Severe or Critical symptoms of disease (per WHO Guidance).  Exclusion Criteria:  Any autoimmune disease or immune-modulator therapy. Mild or Moderate symptoms of COVID-19 disease (per WHO Guidance).