Pooling Nasopharyngeal Swab Specimens to Improve Testing Capacity for SARS-CoV-2 by Real-Time RT-PCR

Table 1 Detection of SARS-CoV-19 RNA by RT-PCR in pooled nasopharyngeal (NP) specimens from patients with COVID-19

Specimen N°	Target	Nonpooled (Ct)			Positive NP specimen pooled with four negative NP specimens (Ct)				Positive NP specimen pooled with nine negative NP specimens (Ct)
Specimen N°	Target	Ct Replicate I	Ct Replicate II	Ct Average	Ct Replicate I	Ct Replicate II	Ct Average	Δ_Ct	Ct Replicate I	Ct Replicate II	Ct Average	Δ_Ct
1	SARS-CoV-2 (orf1ab)	17.85	18.79	18.32	20.59	21.15	20.87	2.55	21.32	22.03	21.67	3.35
2		27.35	26.57	26.96	31.27	30.63	30	3.03	31.35	30.75	31.05	4.09
3		27.39	27.24	27.32	28.58	28.75	28.67	1.35	29.34	29.30	29.32	2
4		28.85	26	27.42	31.53	29.71	30.62	3.2	32.50	32.64	32.57	5.15
5		29.46	29.61	29.53	31.47	31.55	31.52	1.93	34.74	34.65	34.7	5.16
6		30	33.06	31.53	33.8	33.2	33.5	2.46	36.20	36.32	36.26	4.77
7		32.18	32.54	32.36	35.15	34.85	35	2.63	35.76	36.66	36.21	3.8
8		32.56	32.17	32.37	35.82	35.09	35.45	3.08	35.89	36.63	36.26	3.89
9		32	33.36	32.68	36.7	36.64	36.67	3.99	39.43	38.91	39.17	6.49
10		32.15	33.37	32.76	31.9	32.92	32.44	0.32	32.61	33.84	33.22	0.46
11		33.49	33.12	33.30	36.85	33.15	35	1.7	37.09	37.31	36.56	3.26
12		32.7	34.22	33.46	35.19	34.98	35.08	1.62	37.27	37.74	37.50	4.4
13		33.62	33.41	33.52	37.27	35.39	36.33	2.81	37.32	38	37.66	4.14
14		35.23	35.61	35.23	35.51	37.29	36.4	1.16	37.2	38.51	37.85	2.62
15		35.74	35.80	35.77	36.26	36	36.13	0.36	37.46	37.89	37.68	1.91
16		36.52	35.52	36.03	35.63	37.33	36.48	0.45	36.87	37.99	37.43	0.56
17		36.39	35.98	36.18	36.72	36.6	36.66	0.48	37.85	38.23	38.03	1.85
18		36.20	36.33	36.22	37.47	37.05	37.26	1.04	41.1	ND	ND	–
19		37.05	36.58	36.81	37.07	ND	–	–	ND	ND	ND	–
20		38.0	38.32	38.16	38.73	ND	–	–	ND	ND	ND	–
	Mean Δ_Ct ± SD			32.29 ± 4.61			33.56 ± 4.1	1.85 ± 1.09			34.9 ± 4.34	3.4 ± 1.65

Ct Cycle Threshold, ND Not detected, NP Nasopharyngeal, Δ_{Ct Ct individual-Ct pooled}, SD Standard Deviation

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