Table 1.
Factors associated with SARS-CoV-2 seropositivity: univariable analysis
| Total number | Seroprevalence % (95% CI)* | Unadjusted OR (95% CI)† | P value | |
| Overall | 700 | 35.4 (30.2 to 41.0) | – | – |
| Sex | 0.119 | |||
| Male | 287 | 31.5 (24.2 to 40.0) | 1 (ref) | |
| Female | 413 | 39.2 (33.1 to 45.6) | 1.4 (0.92 to 2.1) | 0.119 |
| Age (years) | <0.001 | |||
| 6–14 | 60 | 33.9 (20.0 to 51.3) | 3.0 (1.2 to 7.4) | 0.019 |
| 15–19 | 57 | 50.4 (35.5 to 65.2) | 5.9 (2.6 to 13.3) | <0.001 |
| 20–64 | 468 | 36.1 (30.9 to 41.8) | 3.3 (1.8 to 6.0) | <0.001 |
| ≥65 | 115 | 14.7 (8.9 to 23.2) | 1 (ref) | |
| Obesity‡ | 0.002 | |||
| No | 368 | 28.7 (22.4 to 35.8) | 1 (ref) | |
| Yes | 315 | 44.9 (36.6 to 53.4) | 2.0 (1.3 to 3.2) | 0.002 |
| Other medical conditions§ | 0.744 | |||
| No | 401 | 36.4 (29.7 to 43.5) | 1 (ref) | |
| Yes: one | 161 | 34.0 (25.7 to 43.4) | 0.90 (0.56 to 1.5) | 0.67 |
| Yes: several | 116 | 39.4 (29.3 to 50.6) | 1.1 (0.66 to 2.0) | 0.633 |
| Clinical COVID-19 cases in the household¶ | <0.001 | |||
| No | 437 | 18.6 (14.3 to 23.7) | 1 (ref) | |
| 1 person | 159 | 40.9 (30.7 to 51.9) | 3.0 (1.8 to 5.2) | <0.001 |
| >1 person | 104 | 64.0 (49.5 to 76.2) | 7.8 (4.0 to 15.2) | <0.001 |
| Number of rooms | 0.006 | |||
| 1–2 rooms | 141 | 43.0 (32.4 to 54.2) | 2.1 (1.2 to 3.8) | 0.011 |
| 3 rooms | 185 | 43.9 (34.3 to 54.1) | 2.2 (1.3 to 3.9) | 0.005 |
| ≥4 rooms | 366 | 26.2 (19.6 to 34.0) | 1 (ref) | |
| Number of people per room (except living room)** | 0.001 | |||
| >1 person | 435 | 40.0 (33.5 to 46.9) | 4.0 (2.0 to 8.2) | <0.001 |
| 1 person | 129 | 27.6 (19.1 to 38.2) | 2.3 (1.1 to 5.0) | 0.037 |
| <1 person | 128 | 14.3 (7.9 to 24.6) | 1 (ref) | |
| At least one child in the household | 0.116 | |||
| No | 306 | 29.6 (23.0 to 30.9) | 1 (ref) | |
| Yes | 387 | 37.9 (37.2 to 45.6) | 1.5 (0.9 to 2.3) | 0.116 |
| Went out for work during the lockdown | 0.006 | |||
| No | 670 | 36.5 (31.1 to 42.2) | 1 (ref) | |
| Yes | 30 | 5.4 (1.1 to 22.2) | 0.10 (0.02 to 0.51) | 0.006 |
| Went out for a walk during the lockdown | 0.001 | |||
| Never | 559 | 37.5 (32.0 to 43.4) | 1.2 (0.53 to 2.8) | 0.644 |
| Sometimes (≤1 time a week) | 51 | 9.7 (4.2 to 20.8) | 0.22 (0.07 to 0.71) | 0.012 |
| Almost every day | 87 | 33.0 (18.0 to 52.5) | 1 (ref) | |
*Seroprevalence estimated from weighted data.
†Unadjusted OR with corresponding 95% CIs and p values from univariable logistic regressions.
‡For those aged 18 years or older: BMI ≥30 kg/m2; for those aged 6–17 years: BMI (body mass index) ≥IOTF ((International Obesity Task Force) -30 cut-off points.
§Other medical conditions including: asthma, other respiratory diseases, hypertension, heart disease, treated diabetes, treated cancer (excluding hormone therapy), HIV and immunodeficiency, chronic liver disease, chronic kidney disease, neuromuscular diseases.
¶Clinical COVID-19 cases in the household: number of people, except the respondent, with clinical signs of COVID-19 (cough, fever), a positive RT-PCR test or who consulted for suspected COVID-19 since 24 February 2020.
**Living rooms were excluded, except for single people, in order to measure the potential for isolation in the dwellings. Indicator calculated: ([number of people]/number of rooms−1]).
IOTF, International Obesity Task Force.