| Features | Variable | IgG+ n (%) | IgG− n (%) | P-value |
| Gender | Male | 683 (85.3) | 1514 (86.4) | 0.84 |
| Female | 118 (14.7) | 238 (13.6) | ||
| Age | 18 - 30 | 359 (44.8) | 811 (46.3) | 0.39 |
| 31 - 45 | 342 (42.7) | 774 (42.6) | 0.38 | |
| 46 - 60 | 100 (12.5) | 167 (11.1) | ||
| Profession | Pupil/Student | 131 (16.4) | 292 (16.7) | |
| Officials | 78 (9.7) | 204 (4.6) | 0.06 | |
| Unemployed | 206 (25.7) | 514 (30.7) | 0.79 | |
| Worker | 375 (46.8) | 710 (46.2) | 0.45 | |
| Health workers | 11 (1.4) | 32 (1.8) | ||
| Type of donation | Family | 491 (61.3) | 1041 (59.4) | 1 |
| Volunteers | 253 (31.6) | 593 (33.9) | 0.66 | |
| Regular | 57 (7.1) | 118 (6.7) | ||
| Blood type | O | 403 (50.4) | 968 (55.3) | 0.46 |
| A | 165 (20.6) | 412 (23.5) | 0.69 | |
| B | 191 (23.8) | 324 (18.5) | 0.85 | |
| AB | 42 (5.2) | 48 (2.7) |