Table 1.
Demographic characteristics and medical history of the study participants.
| Total | IgG antibody negative subjects | IgG antibody positive subjects | P | |
|---|---|---|---|---|
| (n = 1022) | (n = 959) | (n = 31) | ||
| Age | ||||
| 18–49 | 468 (45.8) | 449 (46.8) | 9 (29) | ns |
| 50–64 | 274 (26.8) | 252 (26.3) | 9 (29) | |
| ≥ 65 | 280 (27.4) | 258 (26.9) | 13 (41.9) | |
| Gender, F/M | 531 (52) / 491 (48) | 491 (51.2) / 468 (48.8) | 19 (61.3) / 12 (38.7) | ns |
| Housing area, rural/urban | 241 (24.3) / 749 (75.7) | 234 (24.4) / 725 (75.6) | 7 (22.6) / 24 (77.4) | ns |
| Obesity | 218 (21.4) | 209 (21.9) | 5 (16.1) | ns |
| Arterial hypertension | 245 (24) | 227 (23.7) | 9 (29) | ns |
| Diabetes | 72 (7) | 69 (7.2) | 1 (3.2) | ns |
| Chronic lung disease | 44 (4.3) | 40 (4.2) | 2 (6.5) | ns |
| Cardiac pathology | 54 (5.3) | 52 (5.4) | 1 (3.2) | ns |
| Immunosuppressive treatment | 47 (4.6) | 42 (4.4) | 3 (9.7) | ns |
| Cancer diagnosis in the last 5 years | 40 (3.9) | 37 (3.9) | 2 (6.5) | ns |
| COVID-19 symptoms in the last 3 months | 515 (50.4) | 475 (49.5) | 25 (80.6) | < 0.01 |
| Previous negative SARS-CoV2 PCR test | 75 (7.3) | 70 (7.3) | 4 (12.9) | ns |
| Previous diagnosis of COVID-19 by PCR | 4 (0.4) | 1 (0.1) | 2 (6.5) | < 0.01 |
| Rapid test results | ||||
| Positive IgM | 11 (1.1) | 11 (1.1) | – | |
| Positive IgG | 28 (2.7) | - | 28 (90.3) | |
| Positive IgM + IgG | 3 (0.3) | - | 3 (9.7) | - |
| Absence of control band | 32 (3.1) | - | - | |
Qualitative variables are expressed as absolute values and proportions. Comparisons between groups of IgG antibody negative subjects and IgG antibody positive subjects were performed with Fisher's exact test or Pearson's chi-square test as appropriate.