Table 1.
Characteristics of imported cases in Hong Kong by moment of detection (excluding cases with special quarantine arrangements).
| At arrival (N=1102) | Up to day 14 of quarantine (N=782) | After day 14 of quarantine (N=58) | P-value | |
|---|---|---|---|---|
| Age group | ||||
| <20 years | 103 (9.35 %) | 84 (10.7 %) | 7 (12.1 %) | 0.470a |
| 20–39 years | 577 (52.4 %) | 421 (53.8 %) | 31 (53.4 %) | |
| 40–59 years | 350 (31.8 %) | 221 (28.3 %) | 14 (24.1 %) | |
| >59 years | 72 (6.53 %) | 56 (7.16 %) | 6 (10.3 %) | |
| Sex | ||||
| Female | 574 (52.1 %) | 460 (58.8 %) | 44 (75.9 %) | <0.001b |
| Male | 528 (47.9 %) | 322 (41.2 %) | 14 (24.1 %) | |
| Region of importation | ||||
| Asia (not including Southeast Asia) | 330 (30.3 %) | 282 (36.4 %) | 15 (25.9 %) | <0.001b |
| Southeast Asia | 280 (25.7 %) | 280 (36.2 %) | 35 (60.3 %) | |
| Europe | 255 (23.4 %) | 117 (15.1 %) | 4 (6.90 %) | |
| Others | 223 (20.5 %) | 95 (12.3 %) | 4 (6.90 %) | |
| Period of arrival (% by row) | ||||
| First phase (N=258) | 187 (72.5 %) | 68 (26.4 %) | 3 (1.2 %) | <0.001b |
| Second phase (N=561) | 282 (50.3 %) | 239 (42.6 %) | 40 (7.1 %) | |
| Third phase (N=185) | 100 (54.1 %) | 83 (44.9 %) | 2 (1.1 %) | |
| Fourth phase (N=324) | 158 (48.8 %) | 154 (47.5 %) | 12 (3.7 %) | |
| Fifth phase (N=614) | 375 (61.1 %) | 238 (38.8 %) | 1 (0.2 %) | |
| Vaccination status (from 12 May 2021) | ||||
| 2 doses mRNA | 342 (54.0 %) | 202 (42.5 %) | 2 (13.3 %) | <0.001a |
| 2 doses inactivated | 93 (14.7 %) | 124 (26.1 %) | 6 (40.0 %) | |
| Other vaccination courses | 115 (18.2 %) | 72 (15.2 %) | 4 (26.7 %) | |
| Not vaccinated/Not reported | 83 (13.1 %) | 77 (16.2 %) | 3 (20.0 %) | |
| Presence of symptoms | ||||
| Asymptomatic | 851 (77.2 %) | 532 (68.0 %) | 52 (89.7 %) | <0.001b |
| Symptomatic | 251 (22.8 %) | 250 (32.0 %) | 6 (10.3 %) | |
| Variants of concern | ||||
| Omicron | 273 (24.8 %) | 117 (15.0 %) | 0 (0 %) | <0.001a |
| Delta | 245 (22.2 %) | 164 (21.0 %) | 9 (15.5 %) | |
| Other variants (Alpha/Beta/Gamma) | 85 (7.71 %) | 59 (7.54 %) | 7 (12.1 %) | |
| Ancestral strain | 65 (5.90 %) | 55 (7.03 %) | 4 (6.90 %) | |
| Not tested/Indeterminate | 434 (39.4 %) | 387 (49.5 %) | 38 (65.5 %) | |
| RT-PCR Ct-value at isolation | ||||
| Mean (SD) | 28.2 (8.73) | 30.2 (9.79) | 39.8 (6.98) | <0.001c |
| Median [Q1, Q3] | 27.7 [21.1, 33.8] | 30.0 [21.5, 38.5] | 44.0 [36.1, 45.0] | |
| Minimum RT-PCR Ct-value during isolation | ||||
| Mean (SD) | 25.4 (8.22) | 27.9 (9.04) | 36.3 (7.43) | <0.001c |
| Median [Q1, Q3] | 23.6 [18.7, 30.5] | 27.3 [19.9, 34.8] | 36.1 [31.3, 44.6] | |
| RT-PCR Ct-value ever lower than 30 during isolation | ||||
| No | 334 (30.4 %) | 336 (43.2 %) | 49 (84.5 %) | <0.001b |
| Yes | 766 (69.6 %) | 441 (56.8 %) | 9 (15.5 %) | |
a
Fisher's exact test.
b
Chi-square test.
c
Kruskal-Wallis test.