Figure 4.

Inter-assay comparisons reveal high RBD binding assay sensitivity and specificity. Each horizontal line indicates an individual sample tested by one of 8 binding assay methods. ELISA values below the negative cut-off determined by P/N were deemed negative; those above the positive cut-off were considered positive. Values between upper and lower cut-offs were equivocal. 66% (122/186) of samples were seronegative by all serological assays (light blue lines). Panel (a) includes samples tested on PRNT and all 8 binding assays. Panel (b) compares PRNT positive samples (gold standard positive) to the 8 other serological assays.