Table 2.

Clinical Performance of the Elecsys Anti–SARS-CoV-2 S-Ab Assay^a

Semiquantitative S-Ab Assay	Prepandemic	PCR-Positive 0-6 Days	PCR-Positive 7-13 Days	PCR-Positive ≥14 Days
	No Disease	Disease	Disease	Disease
Positive, ≥0.8 U/mL	0	36	25	20
Negative, <0.8 U/mL	53	24	7	0
Total	53	60	32	20

S-Ab, spike protein antibody.

^aData are number of samples. A total of 112 COVID-19 patient samples were collected 0 to 6 days (60 samples), 7 to 13 days (32 samples), or at or more than 14 days (20 samples) after initial confirmation of positivity by reverse transcription quantitative polymerase chain reaction (PCR). The 53 prepandemic samples were collected prior to mid-2019 and were therefore COVID-19 negative by definition.