Table 1.

Validation of DBS eluates on IgG and IgM S1 capture assays.

DBS donor characteristics	Number of DBS tested	Assay used for DBS	Number of DBS reactive	Measured outcome (95% CI)
DABA anti-RBD sero-positive	439	IgG and IgM**	430	Diagnostic sensitivity 97.9% (96.6–99.3)
		IgG alone	404	Diagnostic sensitivity 92.0% (89.5–94.6)
DABA anti-RBD sero-positive*	431	IgG and IgM**	430	Analytical sensitivity 99.8% (99.3–100)
DABA anti-RBD sero-negative	382	IgG	3	Diagnostic specificity 99.2% (98.4–100)

*This number excludes eight donors from the 439 donors whose sera were known to be negative by Ig Capture assay, ** IgG followed by IgM if IgG negative. Specificity and sensitivity shown are based on REACT donors many of whom will have been early convalescent patients.