TABLE 2.

Kappa index for the agreement between all tested methods [Color table can be viewed at wileyonlinelibrary.com]

	nAb20	RBD	OSpk 1.0	R‐NP 1.0	R‐Spk 0.8	ICB‐G	ICB‐M	ICB‐A	OSpk1 + RBD	RSpk0.8 + RBD		nAb160	RBD68	OSpk 9.5	R‐NP 109	R‐SPk 132	ICB‐G 5.0	ICB‐M 5.0	ICB‐A 5.0	OSpk9.5 + RBD	RSpk132 + RBD
nAb20	1.00										nAb160	1.00									Slight
RBD	0.85	1.00									RBD68	0.66	1.00								Fair
OSpk 1.0	0.92	0.84	1.00								OSpk9.5	0.38	0.30	1.00							Mod
R‐NP 1.0	0.86	0.78	0.85	1.00							R‐NP109	0.29	0.29	0.10	1.00						Subs
R‐Spk 0.8	0.92	0.84	1.00	0.85	1.00						R‐Spk132	0.53	0.69	0.21	0.35	1.00					A/pft
ICB‐G	0.89	0.81	0.80	0.75	0.80	1.00					ICB‐G5.0	0.58	0.43	0.35	0.21	0.40	1.00				Pft
ICB‐M	0.11	0.11	0.09	0.13	0.09	0.12	1.00				ICB‐M5.0	0.03	0.03	0.01	0.08	0.06	0.03	1.00
ICB‐A	0.18	0.18	0.15	0.21	0.15	0.19	0.32	1.00			ICB‐A5.0	0.12	0.15	0.03	0.06	0.18	0.12	0.00	1.00
OSpk1+RBD	0.24	0.24	0.28	0.25	0.21	0.26	0.05	0.29	1.00		OSpk9.5+RBD	0.66	1.00	0.30	0.29	0.69	0.43	0.03	0.15	1.00
RSpk0.8+RBD	0.24	0.24	0.20	0.27	0.20	0.25	0.06	0.30	0.99	1.00	RSpk132+RBD	0.16	0.23	0.04	0.59	0.28	0.08	0.14	0.05	0.05	1.00

Note: The kappa results are classified as: <0 (poor); 0–0.20 (slight); 0.21–0.40 (fair); 0.41–0.60 (moderate); 0.61–0.80 (substantial); 0.81–0.99 (almost perfect); 1.00 (perfect). Results in left and right are based on manufacturer's instructions or using only high‐tittered sera compared with FDA authorization, respectively.

Abbreviations: anti‐RBD, competitive anti‐RBD inhibition test; anti‐RBD68, ≥68% competitive anti‐RBD inhibition test; ICB‐A, anti‐IgA NP; ICB‐G, anti‐IgG NP; ICB‐M, anti‐IgM NP; nAb20/160, neutralizing antibody titer ≥20 or ≥160, respectively; NP, nucleoprotein; O‐SPk, Ortho Spike; R‐NP, Roche NP; R‐Spk, Roche Spike; Spk0.8 and Spk1.0, anti‐Spike tests based on the manufacturer's cut‐off; SPk109 and SPk132, anti‐Spike tests based on FDA guidance for high‐titer.