Table 2.

Summary of LOD Results

Molecular assay	Target	No. of replicates detected/total no. of replicates at each dilution expressed by GE/mL (% positive rate)						Probit (±95% CI),∗ GE/mL	Final LOD,† GE/mL
		4000	2000	1000	500	250	125
NWHL LDT	S	4/4	6/6 (100)	9/10 (90)	5/10 (50)	2/8 (25)	1/8 (25)	1301 ± 13	1301 ± 13
Modified CDC assay	N1	4/4	6/6 (100)	9/10 (90)	7/10 (70)	6/8 (75)	1/8 (25)	1249 ± 14	1249 ± 14
	N2	4/4	6/6 (100)	10/10 (100)	5/10 (50)	2/8 (25)	1/8 (25)	946 ± 11

GE/mL, genome equivalents/mL; LOD, limit of detection; NWHL LDT, Northwell Health Laboratories laboratory-developed test.

^∗Upper/lower (±) 95% CI.

^†The final LODs were based on both assays’ results interpretation algorithm and determined by using probit analysis.