IgGimmunoglobulin G(3) Cohort(3) cycle threshold(3) E Proteinenvelope protein(3) envelope protein(3) COVID-19(3) M Proteinmembrane protein(3) ROCreceiver operating characteristic(3) inactivated(3) Biomarker(3) pilot study(3) immunoglobulin M(3) SARS-CoV-2 virus(3) controls(3) WHOWorld Health Organization(3) Receptor binding domain(3) with COVID-19(3) ACE2angiotensin-converting enzyme 2(3) specificity(3) Concordance(3) DTTdithiothreitol(3) membrane protein(3) LoDlimit of detection(3) N Proteinnucleocapsid protein(3) platform(3) Saliva(3) viral envelope protein(3) Analysis(3) CT(3) SARS-CoV-2 strains(3)