Table.

Sensitivity, specificity, positive-predictive value (PPV) and negative-predictive value (NPV) for samples collected in normal saline (NS) tested by real-time reverse transcription-polymerase chain reaction for SARS-CoV-2 (n=135)*

Conditions	True positive	True negative	Totals
Samples detected positive in NS	34 (a)	0 (b)	34 (a+b)
Samples detected negative in NS	1 (c)	100 (d)	101 (c+d)
Total	35 (a+c)	100 (b+d)	135 (a+b+c+d)
Sensitivity		97.1% (a/a+c)
Specificity		100% (d/b+d)
PPV		100% (a/a+b)
NPV		99% (d/c+d)

*VTM collected samples were taken as the gold standard for calculation of sensitivity, specificity, PPV and NPV of NS collected samples. Samples collected in VTM and NS both failed to detect one positive sample out of 35 known positive samples and both VTM and NS missed detection of a different positive sample. As such sensitivity of VTM was 97.1 per cent in comparison to NS collected samples.