Table 1

COVID-19 biomarkers by platform and regulatory approval level

Approval levelBiomarkerPlatformComment
Food and Drug
Administration (FDA) Emergency Use Authorization for
COVID-19
Viral loadPCRHigh viral load predicts mortality113; plasma viremia associated with severity and mortality98
IgG antibody levelLateral flow or other immunoassayHigher antibody levels generated in severe cases,18 22 but pre-existing antibody protective19 22
Clinical assay availableProinflammatory cytokines, especially IL-6ELISA or other immunoassayIL-6 is of interest because it can be targeted by a monoclonal antibody drug
Lymphocyte count from CBC with differentialCoulter counterReduction in lymphocyte count predicts disease severity113
CRP, procalcitonin, troponinImmunoassayIncreased levels predict severity113 or mortality114
CD8+ T cell countT/B/NK flow cytometryDecreased CD8+ T cell counts predict severity101
ExploratoryDeveloping neutrophils, T cell exhaustion, HLA-DRlow monocytes, MDSCs, plasmsablasts, pDC signalingMultiparameter flow cytometry or CyTOFMultiple biomarkers could be assessed with a single flow or mass cytometry panel
Virus-specific
T cell enumeration and function
Flow cytometry with intracellular cytokine staining (ICS) or ELISPOTMany functions could be measured with ICS; two-color Fluorospot assay could measure two cytokines
Multiple serum proteins such as calprotectin, EN-RAGE, GDF-15, IL-6, IL-8, IL-10, IL-15, OSM, PTX3, ST2, TNF, TNSF14 (LIGHT), TNFRSF1AMultiplex immunoassayA combination of cytokines may be most predictive of severe disease4959
Ab specificity for SARS-CoV-2 proteins and heterologous virusesMultiplex immunoassayProtein specificity could influence disease severity23
  • CBC, complete blood cell; CRP, C reactive protein; MDSCs, myeloid-derived suppressor cells; pDC, plasmacytoid dendritic cells.