Table 3.
Multivariate analysis of predictors of a positive SC2-RT-PCR and/or rapid antigen test result for each period.
| Period 1 (original strain) N = 1,825 |
Period 2 (Alpha variant) N = 1,453 |
Period 3 (Delta variant) N = 1,236 |
Period 4 (Omicron variant) N = 822 |
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|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n/N (%) | aOR (95CI) | p-value | n/N (%) | aOR (95CI) | p-value | n/N (%) | aOR (95CI) | p-value | n/N (%) | aOR (95CI) | p-value | |
| Contact | ||||||||||||
| None | 1,559/1,825 (85.4) | 1 | 1,194/1,453 (82.2) | 1 | 172/1,236 (13.9) | 1 | 451/822 (54.9) | 1 | ||||
| Confirmed contact with an infected household adult | 120/1,825 (6.6) | 18.5 (11.2–30.7) | <0.001 | 93/1,453 (6.4) | 33.7 (17.8–63.9) | <0.001 | 426/1,236 (34.5) | 38.9 (19.3–78.7) | <0.001 | 163/822 (19.8) | 5.0 (3.2–7.7) | <0.001 |
| Confirmed contact with an infected household child | 17/1,825 (0.9) | 15.0 (4.8–47.1) | <0.001 | 15/1,453 (1.0) | 28.4 (8.7–92.6) | <0.001 | 316/1,236 (25.6) | 15.1 (5.5–41.7) | <0.001 | 65/822 (7.9) | 5.5 (2.8–10.8) | <0.001 |
| Confirmed contact with an infected adult outside the home | 48/1,825 (2.6) | 13.2 (6.1–28.8) | <0.001 | 57/1,453 (3.9) | 11.5 (4.9–26.9) | <0.001 | 246/1,236 (19.9) | 15.3 (5.5–42.2) | <0.001 | 40/822 (4.9) | 2.3 (1.1–4.5) | 0.02 |
| Confirmed contact with an infected child outside the home | 81/1,825 (4.5) | 1 (0.2–4.4) | 0.98 | 94/1,453 (6.5) | 4.2 (1.9–9.4) | <0.001 | 76/1,236 (6.1) | 6.8 (3.5–12.9) | <0.001 | 103/822 (12.5) | 2.1 (1.3–3.4) | 0.004 |
| Age group | ||||||||||||
| ≤12 months | 333/1,825 (18.1) | 1 | 263/1,453 (18.1) | 1 | 172/1,236 (13.9) | 1 | 210/822 (25.6) | 1 | ||||
| 13–36 months | 805/1,825 (44.1) | 0.6 (0.3–1.0) | 0.05 | 588/1,453 (40.5) | 0.4 (0.2–0.9) | 0.03 | 426/1,236 (34.5) | 0.8 (0.3–2.2) | 0.73 | 315/822 (38.3) | 0.7 (0.5–1.1) | 0.17 |
| 37–72 months | 392/1,825 (21.5) | 1 (0.5–2.0) | 0.94 | 316/1,453 (21.8) | 0.8 (0.4–2.0) | 0.69 | 316/1,236 (25.6) | 3 (1.1–8.1) | 0.03 | 144/822 (17.5) | 1.2 (0.7–2.1) | 0.52 |
| 73 months–11 years | 224/1,825 (12.3) | 1.5 (0.7–3.4) | 0.28 | 235/1,453 (16.2) | 1.5 (0.6–3.4) | 0.36 | 246/1,236 (19.9) | 5.8 (2.1–16.1) | 0.001 | 114/822 (13.9) | 3.6 (2–6.6) | <0.001 |
| ≥12 years | 73/1,825 (4.0) | 1.9 (0.7–5.3) | 0.23 | 51/1,453 (3.5) | 2.8 (0.9–8.5) | 0.07 | 76/1,236 (6.1) | 5.2 (1.5–18.1) | 0.009 | 39/822 (4.7) | 2.9 (1.3–6.5) | 0.009 |
| Daycare center/primary school/secondary school/high school in the last 15 days | ||||||||||||
| Yes | 1,488/1,770 (84.1) | 1 | 1,127/1,354 (83.3) | 1 | 1,068/1,229 (86.9) | 1 | 624/815 (76.6) | 1 | ||||
| No | 282/1,770 (15.9) | 3.5 (2.0–6.2) | <0.001 | 227/1,354 (16.7) | 2.1 (1.1–4) | 0.03 | 161/1,229 (13.1) | 4.1 (2.0–8.4) | <0.001 | 191/815 (23.4) | 2.1 (1.4–3.3) | 0.001 |
| Dyspnea/wheezing | ||||||||||||
| Yes | 1,091/1,332 (18.1) | 1 |
171/1,135 (15.1) | 2.7 (1.4–5.1) |
0.003 |
|||||||
| No | 241/1,332 (81.9) | 2.6 (1.0–7.1) | 0.05 | 964/1,135 (84.9) | 1 | |||||||
| Sore throat | ||||||||||||
| Yes | 399/981 (40.7) | 1 | ||||||||||
| No | 582/981 (59.3) | 2.4 (1.4–4.1) | 0.001 | |||||||||
| Cough | ||||||||||||
| Yes | 482/793 (60.8) | 1 | ||||||||||
| No | 311/793 (39.2) | 1.7 (1.2–2.4) | 0.002 | |||||||||
| Diarrhea | ||||||||||||
| Yes | 120/763 (15.7) | 1 | ||||||||||
| No | 643/763 (84.3) | 2.0 (1.2–3.1) | 0.005 | |||||||||
aOR, adjusted odds ratio; 95CI, 95 % confidence interval.
Significant p-values (<0.05) are in bold.