Table 2.
Comparison of cases and controls.
| Characteristic | Level | Cases (N = 19) | Controls (N = 734) | p |
|---|---|---|---|---|
| Age, years | Median (IQR) | 43 (28–69) | 73 (58–83) | <0.001 a |
| Sex | Female, % (N) | 47.4 (9) | 46.3 (340) | >0.99 b |
| Male, % (N) | 52.6 (10) | 53.7 (394) | ||
| Area | North, % (N) | 42.1 (8) | 12.3 (90) | <0.001 b |
| Center, % (N) | 47.4 (9) | 31.1 (228) | ||
| South, % (N) | 10.5 (2) | 56.7 (416) | ||
| Month of symptom onset | Oct–Nov 2021, % (N) | 0 (0) | 6.1 (45) | 0.003 b |
| Dec 2021, % (N) | 10.5 (2) | 7.1 (52) | ||
| Jan 2022, % (N) | 5.3 (1) | 21.0 (154) | ||
| Feb 2022, % (N) | 5.3 (1) | 24.8 (182) | ||
| Mar 2022, % (N) | 68.4 (13) | 26.2 (192) | ||
| Apr–May 2022, % (N) | 10.5 (2) | 14.9 (109) | ||
| Swab delay, days | Median (IQR) | 3 (0–4) | 2 (0–4) | 0.84 a |
| ≥1 chronic condition | No, % (N) | 73.7 (14) | 73.7 (541) | >0.99 b |
| Yes, % (N) | 26.3 (5) | 26.3 (193) | ||
| COVID-19 vaccination | No, % (N) | 0 (0) | 14.7 (108) | 0.092 b |
| 1 dose, % (N) | 10.5 (2) | 3.5 (26) | ||
| 2 doses, % (N) | 31.6 (6) | 25.3 (186) | ||
| 3 doses, % (N) | 57.9 (11) | 56.4 (414) | ||
| 2020/21 influenza vaccination | No, % (N) | 63.2 (12) | 59.3 (435) | 0.063 b |
| Yes, % (N) | 15.8 (3) | 32.6 (239) | ||
| Unknown, % (N) | 21.1 (4) | 8.2 (60) | ||
| 2021/22 influenza vaccination | No, % (N) | 89.5 (17) | 56.4 (414) | 0.004 b |
| Yes, % (N) | 10.5 (2) | 43.6 (320) |
IQR, Interquartile range; a Mann–Whitney–Wilcoxon test; b Fisher’s exact test.