Table 2.

Sensitivity to detect anti-N IgG antibodies after recent SARS-CoV-2 RT-PCR positive test.

Test week	Last date of PCR reference period	Number of donors tested for anti-N IgG antibodies	Observed seroprevalence among SARS-CoV-2 RT-PCR positives
		N	%
Week 3	January 4, 2022	4 722	77 (70–84)
Week 5	January 18, 2022	5 847	77 (72–82)
Week 7	February1, 2022	5 310	81 (77–85)
Week 9	February 15, 2022	5 771	81 (78–84)
Week 11	March 1, 2022	6 132	79 (76–82)
Week 13	March 15, 2022	6 605	74 (71–77)