Repeated negative RT-PCR in the last 12 months (n=735) Repeated negative RT-PCR in the last 12 months (n=735) Positive RT-PCR (n=270) Positive RT-PCR (n=270) Positive RT-PCR (n=270)
P value
Negative N-Protein IgGa (n= 693) Positive N-Protein IgGb (n=42) Positive N-Protein IgGb (n=42) 9 to 12 months agoc (n=94) 3 to 7 months agod (n=176)
Sex Female (%) Male (%) 484 (69.8) 209 (30.2) 35 (83.3) 7 (16.7) 35 (83.3) 7 (16.7) 66 (70.2) 28 (29.8) 139 (78.0) 37 (21.0)
.03
.03
Age, mean (SD), year 86.2 (0.0) 85.3 (7.0) 85.3 (7.0) 86.6 (9.2) 87.8 (8.2) .05 .05
SARS-CoV-2 N-Protein IgG level ≥ 0.8 signal to cutoff ratio, No. (%)
0
42 (100)
42 (100)
55 (61.1)
144 (83.7)
<.001 between c and d
<.001 between c and d
SARS-CoV-2 N-Protein IgG level, median (IQR) [range], AU/mL
0
3.4 (0.8;7.3), [0.8-7.3] 3.4 (0.8;7.3), [0.8-7.3] 1.0 (0.4;2.6) [0.02-6.1]
3.91 (1.9;5.3) [0.01-8]
<.001 between c and b,d
<.001 between c and b,d
SARS-CoV-2 S-protein IgG level
0-50 AU/mL 288 (41.7) 5 (11.9) 5 (11.9) 8 (4.6) 2 (2.1)
50-1050 AU/mL 343 (49.6) 5 (11.9) 5 (11.9) 15 (8.6) 6 (6.4)
1050-4160 AU/mL 47 (6.8) 1 (2.4) 1 (2.4) 5 (2.8) 3 (3.2)
≥ 4160 AU/mL 13 (1.9) 31 (73.8) 31 (73.8) 147 (84.0) 83 (88.3)
SARS-CoV-2 S-protein level median (Q1-Q3) [range], AU/mL
82 (16-296)[0-40,000]
21,736 (16,229) [0-40,000] 21,736 (16,229) [0-40,000]
40,000 (9,146-40,000) [6-14142]
20,796 (4157;40000) [1-40,000]
<.001 between a and b,c,d <.001 between c and b,d <.001 between a and b,c,d <.001 between c and b,d