Table 2.

Diagnostic performance of SARS-CoV-2 total antibody ELISA.

	4 – 69 days post symptom onset	4 – 14 days post symptom onset	>14 days post symptom onset
Sensitivity (95% CI)	86.1% (76.4–92.8%)n = 316§	71.8% (55.1–85.0%)n = 276§§	100% (91.2–100.0%)n = 277§§§
Specificity (95% CI)	100% (98.5–100.0%)
Positive predictive value#	100%; 100%
Negative predictive value (95% CI)#	99.8% (99.6–99.9%);99.3% (98.8–99.9%)	99.6% (99.3–99.7%);98.5% (97.6–99.1%)	100%; 100%

Three of the 210 pre-pandemic samples with equivocal SARS-CoV-2 antibody indices were excluded from the diagnostic performance calculations.

PCR, polymerase chain reaction; CI, confidence interval.

^#Values assuming 1.5% disease prevalence; 5% disease prevalence.

^§79 PCR positive, 30 PCR negative, 207 pre-pandemic (presumed PCR negative).

^§§39 PCR positive, 30 PCR negative, 207 pre-pandemic (presumed PCR negative).

^§§§40 PCR positive; 30 PCR negative, 207 pre-pandemic (presumed PCR negative).