Table 3.
Adjusted prevalence and odds ratio of seropositivity to IgG antibodies against SARS-CoV-2 by categories of risk exposure and covariates.
| SARS-CoV-2 IgG seropositivity |
Odds Ratio (95%CI), p-value |
|||||
|---|---|---|---|---|---|---|
| N | n | % (95%CI) | Unadjusted | Fully adjusted | Mutually adjusted | |
| Hospital site | ||||||
| Low risk | 3729 | 336 | 8.25 (7.33–9.25) | 1 (ref) | 1 (ref) | 1 (ref) |
| High risk | 997 | 118 | 11.17 (9.21–13.37) | 1.40 (1.10–1.78), 0.007 | 1.38 (1.08–1.78), 0.011 | 1.01 (0.76–1.34), 0.932 |
| Hospital ward /unit type | ||||||
| Low risk | 3426 | 276 | 7.27 (6.36–8.27) | 1 (ref) | 1 (ref) | 1 (ref) |
| Medium risk | 317 | 34 | 10.73 (7.60–14.57) | 1.42 (0.94–2.15), 0.096 | 1.39 (0.91–2.13), 0.126 | 1.30 (0.86–1.98), 0.211 |
| High risk | 983 | 144 | 14.07 (11.88–16.51) | 2.09 (1.65–2.64), <0.001 | 1.98 (1.55–2.53), <0.001 | 1.91 (1.45–2.51), <0.001 |
| HCW category | ||||||
| Low risk | 1032 | 76 | 6.56 (5.02–8.37) | 1 (ref) | 1 (ref) | 1 (ref) |
| Medium risk | 445 | 35 | 7.08 (4.78–10.01) | 1.18 (0.74–1.91), 0.485 | 1.28 (0.78–2.09), 0.332 | 1.08 (0.67–1.75), 0.759 |
| High risk | 3173 | 343 | 10.11 (9.02–11.28) | 1.75 (1.30–2.35), <0.001 | 1.75 (1.28–2.40), 0.001 | 1.49 (1.10–2.03), 0.011 |
| Age group | ||||||
| 16–40 | 2191 | 237 | 10.12 (8.83–11.54) | 1 (ref) | 1 (ref) | – |
| 41–50 | 1289 | 123 | 8.81 (7.21–10.59) | 0.86 (0.67–1.10), 0.234 | 0.83 (0.64–1.08), 0.175 | – |
| >51 | 1244 | 94 | 6.76 (5.31–8.39) | 0.64 (0.49–0.85), 0.002 | 0.63 (0.47–0.85), 0.002 | – |
| Gender | ||||||
| Women | 3229 | 319 | 9.15 (8.11–10.27) | 1 (ref) | 1 (ref) | – |
| Men | 1496 | 135 | 8.27 (6.82–9.87) | 0.90 (0.71–1.13), 0.355 | 0.84 (0.65–1.08), 0.167 | – |
| BMI (kg/m2) | ||||||
| <25 | 3116 | 293 | 8.66 (6.64–9.78) | 1 (ref) | 1 (ref) | – |
| 25–29.9 | 1121 | 101 | 8.26 (6.61–10.11) | 0.95 (0.73–1.24), 0.698 | 1.04 (0.79–1.37), 0.776 | – |
| ≥30 | 377 | 47 | 11.82 (8.56–15.70) | 1.41 (0.99–2.02), 0.057 | 1.51 (1.04–2.17), 0.028 | – |
| Smoking | ||||||
| No | 3572 | 370 | 9.65 (8.64–10.73) | 1 (ref) | 1 (ref) | – |
| Yes | 1154 | 84 | 6.47 (4.99–8.15) | 0.65 (0.49–0.86), 0.003 | 0.63 (0.47–0.84), 0.002 | – |
| Flu vaccination | ||||||
| No | 2543 | 220 | 7.93 (6.83–9.12) | 1 (ref) | 1 (ref) | – |
| Yes | 2183 | 233 | 9.97 (8.68–11.38) | 1.29 (1.04–1.59), 0.021 | 1.27 (1.01–1.58), 0.038 | – |
| Contact COVID-19 | ||||||
| No | 4325 | 360 | 7.73 (6.89–8.64) | 1 (ref) | 1 (ref) | – |
| Yes | 491 | 94 | 18.71 (15.28–22.54) | 2.75 (2.11–3.58), <0.001 | 2.80 (2.14–3.67), <0.001 | |
95%CI: 95% Confidence Intervals.
Ref = Referent category.
Unadjusted estimates are from univariate models. Fully adjusted estimates are from models adjusted for all covariates (age group, gender, BMI, smoking, flu vaccination, and contact COVID-19) and one single category of risk exposure at a time (fully adjusted estimates pertaining to the covariates are from a model including all covariates and no categories of risk exposure). Mutually adjusted estimates are from a model including only categories of risk exposure.