Table 2. Baseline characteristics of 454 household contacts stratified by index case Alpha or non-VOC SARS-CoV-2 status.
| Non-VOC index case household | Alpha index case household | ||
|---|---|---|---|
| Number of contacts—n | 102 | 352 | |
| Index Characteristics | |||
| HHC exposed to a female index—n (%) | 58 (57) | 197 (56) | |
| Index age HHC exposed to—median (IQR) | 62 (45–76) | 56 (47–69) | |
| HHC exposed to index ethnicity | white (%) | 47 (46) | 163 (46) |
| Asian (%) | 6 (6) | 24 (7) | |
| Black (%) | 11 (11) | 72 (21) | |
| Middle Eastern (%) | 14 (14) | 19 (5) | |
| SE Asian (%) | 21 (21) | 39 (11) | |
| other | 3 (3) | 35 (10) | |
| Hospital site | Hospital 1 | 49 (48) | 173 (49) |
| Hospital 2 | 53 (52) | 179 (51) | |
| household size–median (IQR) | 3 (2–4) | 3 (2–4) | |
| HHC exposed to index case respiratory symptoms1 –n (%) | 71 (70) | 276 (78) | |
| HHC exposure to symptomatic index in days–median (IQR) | 7 (4–12) | 7 (4–12) | |
| HHC exposure to a hospitalised index–n (%) | 62 (61) | 244 (69) | |
| HHC exposure to an index requiring ICU admission–n (%) | 11 (19) | 86 (35) | |
| HHC exposure to an index who died–n (%) | 8 (8) | 33 (9) | |
| Household IMD decile (IQR) | 3 (2–6) | 3 (2–6) | |
| Time since index PCR diagnosis—median (IQR) | 146 (125–181) | 119 (93–157) | |
| Contact characteristics | |||
| contact female–n (%) | 57 (56) | 204 (58) | |
| contact age–median (IQR) | 44 (22–59) | 42 (24–60) | |
| days of exposure to index–median (IQR) | 4 (1–10) | 7 (3–14) | |
| proximity to index2 –n (%) | no close contact | 19(19) | 49(14) |
| assisted in personal care | 24 (24) | 130 (37) | |
| shared bedroom | 16 (16) | 59 (17) | |
| shared bathroom | 43 (42) | 114 (32) | |
| other COVID exposure (not index)–n (%) | 26 (26) | 107 (30) | |
| COVID-19 diagnosis–n (%) | 48 (47) | 235 (67) | |
| Contact symptoms—n (%) | 40 (39) | 183 (52) | |
| Long COVID3—n (%) | 4 (4) | 8 (2) | |
| vaccination status at time of serum sampling4 | unvaccinated | 49 (48) | 169 (48) |
| single vaccination | 24 (24) | 102 (29) | |
| double vaccination | 29 (28) | 81 (23) | |
1 any of cough, dyspnoea, flu-like symptoms
2 this variable captures the intensity of contact—level ‘0’ no close contact but still being a household member; level ‘1’ sharing a bathroom but not sharing a bedroom; level ‘2’ sharing a bedroom but not providing physical assistance; level ‘3’ ascribed to those providing physical assistance to the unwell index case including washing, dressing, feeding, assisting with movement
3 individuals with a clinical diagnosis of ‘Long COVID’
4 no more than 2 vaccinations available at this time