Table 1.
Socio-demographics characteristics of the index cases and declared contacts for the whole study period (Overall) and stratified per periods of variant predominance
| Overall | EU1 | Alpha | Delta | Omicron | Missing (%) | |
|---|---|---|---|---|---|---|
| Number of index cases | 50973 | 17460 | 8140 | 11390 | 13983 | |
| Mean number of contact (SD) per index case | 2.19 (1.90) | 2.42 (2.33) | 2.49 (1.86) | 2.39 (1.88) | 1.56 (0.94) | |
| Delay [days] between test result and first contact (phone or form) (SD) | 1.39 (1.38) | 1.68 (1.72) | 0.77 (0.72) | 1.35 (1.09) | 2.05 (1.49) | 39.1 |
| Index who died from COVID-19 (%) | 206 (0.4) | 122 (0.7) | 49 (0.6) | 27 (0.2) | 8 (0.1) | 0 |
| Total number of contacts | 111674 | 42295 | 20311 | 27260 | 21808 | |
| Number of infected contacts within 10 days following contact (%) | 21435 (19.2) | 6922 (16.4) | 4238 (20.9) | 4545 (16.7) | 5730 (26.3) | 0.0 |
| Index Socio-economic- neighbourhood (%) | 3.3 | |||||
| Healthy | 39640 (36.3) | 14713 (35.4) | 7059 (35.1) | 10591 (40.1) | 7277 (34.7) | |
| Slightly vulnerable | 18154 (16.6) | 6570 (15.8) | 3585 (17.8) | 4249 (16.1) | 3750 (17.9) | |
| Moderatly vulnerable | 19533 (17.9) | 7575 (18.2) | 3717 (18.5) | 4446 (16.8) | 3795 (18.1) | |
| Highly vulnerable | 31728 (29.1) | 12713 (30.6) | 5729 (28.5) | 7114 (26.9) | 6172 (29.4) | |
| Index vulnerable person (%) | 8605 (7.9) | 3320 (8.0) | 2098 (10.4) | 2122 (8.0) | 1065 (5.1) | 2.2 |
| Index with symptoms (%) | 98254 (94.1) | 37671 (95.8) | 18464 (91.7) | 24273 (92.5) | 17846 (95.4) | 6.7 |
| Index with cough (%) | 60244 (57.7) | 21700 (55.2) | 11932 (59.2) | 14969 (57.1) | 11643 (62.2) | 6.7 |
| Index obesity (%) | 9351 (10.5) | 3544 (11.7) | 2168 (11.3) | 2045 (8.4) | 1594 (10.3) | 20.1 |
| Index women (%) | 59738 (53.6) | 22520 (53.3) | 10938 (53.9) | 14325 (52.8) | 11955 (55.1) | 0.2 |
| Index age category (%) | 0.0 | |||||
| 18–65 | 82118 (73.5) | 35576 (84.1) | 14769 (72.7) | 15891 (58.3) | 15882 (72.9) | |
| 0–17 | 24384 (21.8) | 4264 (10.1) | 4588 (22.6) | 10198 (37.4) | 5334 (24.5) | |
| 65+ | 5153 (4.6) | 2454 (5.8) | 954 (4.7) | 1165 (4.3) | 580 (2.7) | |
| Index immune status (%) | 0.0 | |||||
| Infected <6 months | 638 (0.6) | 252 (0.6) | 169 (0.8) | 46 (0.2) | 171 (0.8) | |
| Infected > 6 months | 1286 (1.2) | 66 (0.2) | 56 (0.3) | 351 (1.3) | 813 (3.7) | |
| hybrid | 1269 (1.1) | 0 (0.0) | 10 (0.0) | 139 (0.5) | 1120 (5.1) | |
| Non-vaccinated non-infected (NVNI) | 90156 (80.7) | 41977 (99.2) | 19721 (97.1) | 18995 (69.7) | 9463 (43.4) | |
| Vaccinated < 6 months | 11853 (10.6) | 0 (0.0) | 355 (1.7) | 5974 (21.9) | 5524 (25.3) | |
| Vaccinated > 6 months | 6471 (5.8) | 0 (0.0) | 0 (0.0) | 1754 (6.4) | 4717 (21.6) | |
| Index housing type (%) | 2.2 | |||||
| Building | 88690 (80.6) | 33623 (80.2) | 16333 (80.8) | 21113 (79.0) | 17621 (83.0) | |
| Single house | 18309 (16.6) | 6827 (16.3) | 3402 (16.8) | 5031 (18.8) | 3049 (14.4) | |
| Collective structure | 3105 (2.8) | 1492 (3.6) | 481 (2.4) | 584 (2.2) | 548 (2.6) | |
| Contact type (%) | 38.2 | |||||
| Same roof | 43993 (62.6) | 14402 (55.7) | 12121 (64.7) | 13315 (65.4) | 4155 (77.2) | |
| Intimate or familial | 19409 (27.6) | 8003 (31.0) | 5053 (27.0) | 5448 (26.8) | 905 (16.8) | |
| During the day | 6920 (9.8) | 3450 (13.3) | 1546 (8.3) | 1603 (7.9) | 321 (6.0) | |
| Contact female (%) | 56369 (51.7) | 21018 (51.0) | 10415 (52.0) | 13955 (52.7) | 10981 (51.4) | 2.3 |
| Contact immune status (%) | 9.5 | |||||
| Infected < 6 months | 5253 (5.2) | 1715 (4.4) | 1003 (5.3) | 1390 (6.2) | 1145 (5.5) | |
| Infected > 6 months | 1727 (1.7) | 177 (0.5) | 202 (1.1) | 585 (2.6) | 763 (3.6) | |
| hybrid | 3114 (3.1) | 0 (0.0) | 51 (0.3) | 1197 (5.3) | 1866 (8.9) | |
| Non-vaccinated non-infected (NVNI) | 77005 (76.1) | 36985 (95.1) | 16892 (88.8) | 11863 (52.9) | 11265 (53.8) | |
| Vaccinated < 6 months | 10271 (10.1) | 0 (0.0) | 871 (4.6) | 6337 (28.3) | 3063 (14.6) | |
| Vaccinated > 6 months | 3879 (3.8) | 0 (0.0) | 0 (0.0) | 1042 (4.6) | 2837 (13.5) | |
| Contact age category (%) | 9.9 | |||||
| 18–65 | 63671 (63.2) | 27275 (70.3) | 11230 (59.1) | 13228 (59.1) | 11938 (58.2) | |
| 0–18 | 31798 (31.6) | 9305 (24.0) | 6662 (35.1) | 7912 (35.3) | 7919 (38.6) | |
| 65+ | 5255 (5.2) | 2243 (5.8) | 1110 (5.8) | 1253 (5.6) | 649 (3.2) | |
| Number of tests last 3 months (%) | 0.0 | |||||
| 0 | 22031 (19.7) | 7249 (17.1) | 4289 (21.1) | 5249 (19.3) | 5244 (24.0) | |
| 1 | 80883 (72.4) | 33891 (80.1) | 14580 (71.8) | 19307 (70.8) | 13105 (60.1) | |
| 2+ | 8760 (7.8) | 1155 (2.7) | 1442 (7.1) | 2704 (9.9) | 3459 (15.9) | |
| Number of contacts who performed a test during the 10 days following their contact with the index (%) | 46417 (41.6) | 13392 (31.7) | 12808 (63.1) | 11043 (40.5) | 9174 (42.1) | 0.0 |
| Number of contacts who died from COVID-19 (%) | 130 (0.1) | 20 (0.1) | 18 (0.1) | 86 (0.2) | 6 (0.03) | 0.0 |