Table 2:

Receiver-operator (ROC) curve analysis of SARS-CoV-2 spike-specific IgG and IgA antibody tests at three different dilutions of control and convalescent antisera.

Antibody class	Serum dilution	Positivesa (N)	Negativesb (N)	AUCc [−/+ 95% CI]d	Sens. at 99% spec.e [−/+ 95% CI]	P value
IgG	1:100	197	216	0.96–0.99	75–86	<0.0001
IgG	1:1,000	197	216	0.96–0.99	83–92	<0.0001
IgG	1:10,000	197	216	0.95–0.98	65–78	<0.0001
IgA	1:40	197	133	0.89–0.95	64–76	<0.0001
IgA	1:200	197	133	0.91–0.96	63–76	<0.0001
IgA	1:1,000	197	133	0.88–0.94	45–59	<0.0001

^aConvalescent donor cohort (Conv)

^bPre-COVID cohort (Ctrl)

^cArea under the curve

^d95% confidence intervals

^eTest sensitivity at 99% specificity