Table 2

Factors associated with seroprevalence of anti-SARS-CoV-2 nucleocapsid protein antibodies, Navarre, Spain, 26 April–3 June 2022 (n = 1,461)

Participants Anti -N -positive Crude analysis Adjusted analysis
n n % cOR 95% CI aOR 95% CI
Male 665 391 58.8 Reference Reference
Female 796 469 58.9 1.01 0.82–1.24 0.87 0.66–1.15
5–17 181 154 85.1 Reference Reference
18–29 153 124 81.0 0.75 0.42–1.33 0.91 0.46–1.81
30–39 136 99 72.8 0.47 0.27–0.82 0.36 0.18–0.73
40–49 208 133 63.9 0.31 0.19–0.51 0.40 0.21–0.76
50–59 252 146 57.9 0.24 0.15–0.39 0.37 0.20–0.70
60–69 234 100 42.7 0.13 0.08–0.21 0.29 0.15–0.56
70–79 201 79 39.3 0.11 0.07–0.19 0.30 0.15–0.58
≥ 80 96 25 26.0 0.06 0.03–0.11 0.14 0.06–0.33
Spain 1,274 725 56.9 Reference Reference
Other 187 135 72.2 1.97 1.40–2.76 1.73 1.11–2.69
No 839 536 63.9 Reference Reference
Immunocompromised 41 12 29.3 0.23 0.12–0.47 0.35 0.13–0.93
Other chronic condition 551 287 52.1 0.61 0.49–0.76 0.93 0.68–1.26
Unknown 30 25 83.3 NA NA
No 911 346 38.0 Reference Reference
Yes 525 494 94.1 26.02 17.68–38.31 22.10 14.54–33.58
Unknown 25 20 80.0 NA NA
Unvaccinated 107 90 84.1 Reference Reference
Partial 64 59 92.2 2.23 0.78–6.37 0.50 0.15–1.70
Complete 404 338 83.7 0.97 0.54–1.73 0.70 0.36–1.35
Complete + one booster dose 778 339 43.6 0.15 0.09–0.25 0.33 0.17–0.62
Complete + two booster doses 89 18 20.2 0.05 0.02–0.10 0.18 0.07–0.41
Unknown 19 16 84.2 NA NA

aOR: adjusted odds ratio; CI: confidence interval; cOR: crude odds ratio; COVID-19: coronavirus disease; NA: not applicable (because categories with unknown values were not included in the models); SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.