Table 4.

Specificity of SARS-COV-2 serum N protein assay at the CUT-OFF value recommended by the manufacturer or calculated by using the ROC curve.

Sample source	No. of sample	The CUT-OFF value recommended by the manufacturer		The CUT-OFF value calculated by using the ROC curve
		Number of antigen positive samples	Specificity (%)	No. of N protein positive sample	Specificity (%)
Serum samples of pregnant women	100	0	100	9	91.0
Serum samples with other respiratory infections	369	0	100	10	97.3
Serum samples with elevated rheumatoid factor	119	0	100	0	100
Hemolytic samples	45	0	100	1	97.8
Total	633	0	100	20	96.8