Table 1.
Baseline characteristics of study cohort.
| Characteristic | Delta (B.1.617.2) variant |
Omicron (B.1.1.529) variant |
||||
|---|---|---|---|---|---|---|
| SARS-CoV-2 Positive (N = 546) | SARS-CoV-2 Negative (N = 935) | P-value | SARS-CoV-2 Positive (N = 372) | SARS-CoV-2 Negative (N = 721) | P-value | |
| Vaccination status | <0.001 | 0.040 | ||||
| Vaccinateda | 90 (16%) | 608 (65%) | 187 (50%) | 410 (57%) | ||
| Unvaccinated | 456 (84%) | 327 (35%) | 185 (50%) | 311 (43%) | ||
| Age - median years (IQR) | 52 (38–72) | 77 (59–85) | <0.001 | 75 (51–85) | 75 (56–84) | 0.4 |
| Sex | 0.053 | 0.6 | ||||
| Male | 298 (55%) | 461 (49%) | 193 (52%) | 362 (50%) | ||
| Female | 248 (45%) | 474 (51%) | 179 (48%) | 359 (50%) | ||
| LTCF Resident | 17 (3.1%) | 62 (6.6%) | 0.004 | 28 (7.5%) | 31 (4.3%) | 0.033 |
| Ethnicity | <0.001 | 0.3 | ||||
| White British | 283 (52%) | 717 (77%) | 255 (69%) | 510 (71%) | ||
| Other | 123 (23%) | 66 (7.1%) | 43 (12%) | 63 (8.8%) | ||
| Unknown | 140 (26%) | 152 (16%) | 74 (20%) | 147 (20%) | ||
| Index of multiple deprivation | 5 (3–7) | 5 (3–8) | <0.001 | 5 (3–8) | 5 (3–8) | >0.9 |
| Unknown | 13 | 13 | 23 | 54 | ||
| Smoking | <0.001 | 0.4 | ||||
| Current | 28 (5.1%) | 99 (11%) | 43 (12%) | 73 (10%) | ||
| Ex-smoker | 161 (29%) | 406 (43%) | 122 (33%) | 275 (38%) | ||
| Non-smoker | 288 (53%) | 345 (37%) | 153 (41%) | 275 (38%) | ||
| Unknown | 69 (13%) | 85 (9.1%) | 0 | 1 | ||
| Comorbidity scores | ||||||
| Rockwood Frailty scale | <0.001 | 0.5 | ||||
| 1–4 | 334 (61%) | 409 (44%) | 126 (34%) | 260 (36%) | ||
| 5–10 | 212 (39%) | 525 (56%) | 246 (66%) | 461 (64%) | ||
| CCI – median (IQR) | 1 (0–4) | 4 (2–6) | <0.001 | 4 (1–5) | 4 (2–6) | 0.093 |
| Respiratory | ||||||
| Any | 124 (23%) | 431 (46%) | <0.001 | 126 (34%) | 335 (46%) | <0.001 |
| COPD | 42 (7.7%) | 246 (26%) | <0.001 | 65 (17%) | 194 (27%) | <0.001 |
| Asthma | 73 (13%) | 162 (17%) | 0.047 | 59 (16%) | 113 (16%) | >0.9 |
| Otherb | 21 (3.8%) | 82 (8.8%) | <0.001 | 12 (3.2%) | 73 (10%) | <0.001 |
| Cardiovascular | ||||||
| Any | 80 (15%) | 372 (40%) | <0.001 | 119 (32%) | 266 (37%) | 0.11 |
| IHD | 39 (7.1%) | 120 (13%) | <0.001 | 49 (13%) | 91 (13%) | 0.8 |
| AF | 20 (3.7%) | 184 (20%) | <0.001 | 60 (16%) | 129 (18%) | 0.5 |
| CCF | 22 (4%) | 146 (16%) | <0.001 | 34 (9.1%) | 113 (16%) | 0.003 |
| Diabetes | ||||||
| Any | 63 (12%) | 175 (19%) | <0.001 | 69 (19%) | 124 (17%) | 0.6 |
| Type 1 | 3 (0.5%) | 12 (1.3%) | 0.8 | 5 (1.3%) | 10 (1.4%) | >0.9 |
| Type 2 | 60 (10.9%) | 163 (17.4%) | 64 (1.7%) | 114 (15.8%) | ||
| Neurological | ||||||
| Dementia | 12 (2.2%) | 73 (7.8%) | <0.001 | 26 (7.0%) | 45 (6.2%) | 0.7 |
| Cognitive impairment | 8 (1.5%) | 44 (4.7%) | <0.001 | 20 (5.4%) | 18 (2.5%) | 0.022 |
| CVA | 11 (2.0%) | 67 (7.2%) | <0.001 | 17 (4.6%) | 38 (5.3%) | 0.7 |
| TIA | 12 (2.2%) | 49 (5.2%) | 0.004 | 16 (4.3%) | 37 (5.1%) | 0.7 |
| Other neurological diseasec | 14 (2.6%) | 31 (3.3%) | 0.5 | 24 (6.5%) | 26 (3.6%) | 0.046 |
| Oncology | ||||||
| Solid organ cancer | 22 (4.0%) | 101 (11%) | <0.001 | 29 (7.8%) | 66 (9.2%) | 0.5 |
| Haematological malignancy | 13 (2.4%) | 16 (1.7%) | 0.4 | 8 (2.2%) | 10 (1.4%) | 0.5 |
| Renal diseased | <0.001 | 0.081 | ||||
| None | 488 (89%) | 696 (74%) | 282 (76%) | 565 (78%) | ||
| Mild | 45 (8.2%) | 211 (23%) | 68 (18%) | 133 (18%) | ||
| Moderate/severe | 13 (2.4%) | 28 (3.0%) | 22 (5.9%) | 22 (3.1%) | ||
Data are N (%) unless otherwise stated.
AF, atrial fibrillation; CCF, congestive cardiac failure; CCI, Charlson Comorbidity Index; COPD, chronic obstructive pulmonary disease; CKD; chronic kidney disease; CVA, cerebrovascular accident; IHD, ischaemic heart disease; IQR, interquartile range; LTCF, long-term care facility; TIA, transient ischaemic attack.
Vaccinated are individuals who have received two doses and three doses of BNT162b2 for Delta and Omicron variant respectively.
Includes bronchiectasis, pulmonary fibrosis, and other chronic respiratory conditions.
Includes Parkinson's disease, Huntingdon's disease, and other chronic neurological conditions.
Mild is CKD stage 1–3; moderate or severe is CKD stage 4–5, end-stage renal failure, or dialysis dependence.