(b)
Group	Euro S1-IgA	Euro S1-IgG	Euro NCP-IgG	sVNT (20% c/o)	svnt-20 (20% c/o/equ)	svnt-25 (25% c/o)	Wantai IgM	Wantai Total Ab
Sensitivity	Overall % Agreement (% Best, % Worst)
		Panel A					Panel B
Infected RT-PCR pos	80% (62%, 91%)	79% (61%, 92%)	84% (66%, 95%)	84% (65%, 95%)	83% (64%, 94%)	81% (62%, 94%)	91% (67%, 99%)	86% (62%, 97%)
Days from symptom onset	% Agreement (95% CI) [Pos/Total]
<7 days	57%	67%	75%	71%	71%	71%	90%	80%
	(34%, 78%)	(43%, 85%)	(51%, 91%)	(48%, 89%)	(48%, 89%)	(48%, 89%)	(55%, 100%)	(44%, 97%)
	[12 / 21]	[14 / 21]	[15 / 20]	[15 / 21]	[15 / 21]	[15 / 21]	[9 / 10]	[8 / 10]
7–14 days	85%	77%	81%	85%	85%	81%	89%	79%
	(65%, 96%)	(56%, 91%)	(61%, 93%)	(65%, 96%)	(65%, 96%)	(61%, 93%)	(67%, 99%)	(54%, 94%)
	[22 / 26]	[20 / 26]	[21 / 26]	[22 / 26]	[22 / 26]	[21 / 26]	[17 / 19]	[15 / 19]
>14 days	97%	95%	97%	95%	92%	92%	93%	98%
	(86%, 100%)	(82%, 99%)	(86%, 100%)	(82%, 99%)	(79%, 98%)	(79%, 98%)	(80%, 98%)	(87%, 100%)
	[37 / 38]	[36 / 38]	[37 / 38]	[36 / 38]	[35 / 38]	[35 / 38]	[38 / 41]	[40 / 41]
Specificity	% Agreement (95% CI) [Pos/Total]
Population	55%	90%	100%	100%	100%	70%	100%	100%
	(32%, 77%)	(68%, 99%)	(83%, 100%)	(83%, 100%)	(83%, 100%)	(46%, 88%)	(77%, 100%)	(77%, 100%)
	[11 / 20]	[18 / 20]	[20 / 20]	[20 / 20]	[20 / 20]	[14 / 20]	[14 / 14]	[14 / 14]
Cross-reactive	75%	80%	50%	80%	80%	40%	0%	0%
	(19%, 99%)	(28%, 99%)	(6.8%, 93%)	(28%, 99%)	(28%, 99%)	(5.3%, 85%)	(0%, 98%)	(0%, 98%)
	[3 / 4]	[4 / 5]	[2 / 4]	[4 / 5]	[4 / 5]	[2 / 5]	[0 / 1]	[0 / 1]

Abbreviations: Ab, antibody; c/o, cutoff; equ, equivocal; Euro, Euroimmun; Ig, immunoglobulin; NCP, nucleocapsid; pos, positive; sVNT; GenScript surrogate virus neutralization test.

^aGroup A—49% of sera (>14 days–post symptom onset); Group B—69% of sera (>14 days post–symptom onset).

^bGroup A—49% of sera (>14 days post–symptom onset); Group B—69% of sera (>14 days post–symptom onset)