Table 2. Severe acute respiratory syndrome coronavirus 2 external quality assessment panel homogeneity tests of triplicate test results of 3 samples using the NucliSENS easyMAG extraction and Allplex nCoV-2019 kits performed at the Asan Medical Center, Seoul, South Korea, as a proficiency test provider, March 23, 2020*.

Sample no.	E gene			RdRp gene			N gene
	Mean Ct	%CV		Mean Ct	%CV		Mean Ct	%CV
41	33.82	4.5		34.37	1.6		34.38	0.5
42	25.15	1.4		25.67	1.8		26.67	0.5
43	30.33	1.5		31.34	1.5		31.55	0.7
44	ND	ND		ND	ND		ND	ND
45	27.52	2.2		28.73	0.3		29.05	0.7
46	24.47	0.7		26.12	0.3		27.05	0.2
47	ND	ND		ND	ND		ND	ND
48	20.68	2.5		22.49	0.6		23.49	0.3
49	31.07	0.8		32.55	0.6		33.32	0.9
50	27.89	0.9		29.45	0.2		30.35	0.6

*C_t, cycle threshold; EQA, external quality assessment; %CV, percentage coefficient of variation; ND, not detected.