Baselines characteristics of people with COVID-19, within the CHIA database cohort, stratified by influenza vaccination status
| Characteristics | Influenza vaccination received | ||
| Total | Yes | No | |
| N | 6921 | 2613 | 4308 |
| Age baseline, mean (SD) | 52.4 (24.5) | 61.7 (24.0) | 46.7 (22.9) |
| Female, n (%) | 4120 (59.5) | 1577 (60.4) | 2543 (59.0) |
| Ethnicity, n (%) | |||
| Asian | 328 (4.7) | 98 (3.8) | 230 (5.3) |
| Black | 54 (0.8) | 17 (0.7) | 37 (0.9) |
| Missing data | 2273 (32.8) | 704 (26.9) | 1569 (36.4) |
| Mixed or other | 101 (1.5) | 24 (0.9) | 77 (1.8) |
| White | 4165 (60.2) | 1770 (67.7) | 2395 (55.6) |
| Socioeconomic status (IMD), n (%) | |||
| 1 (most deprived) | 617 (8.9) | 244 (9.3) | 373 (8.7) |
| 2 | 1055 (15.2) | 328 (12.6) | 727 (16.9) |
| 3 | 1207 (17.4) | 477 (18.3) | 730 (16.9) |
| 4 | 1586 (22.9) | 599 (22.9) | 987 (22.9) |
| 5 (least deprived) | 2268 (32.8) | 917 (35.1) | 1351 (31.4) |
| Missing | 188 (2.7) | 48 (1.8) | 140 (3.2) |
| Frailty score, mean (SD) | 0.2 (0.2) | 0.3 (0.2) | 0.1 (0.1) |
| Frailty score, median (IQR) | 0.1 (0.1–0.3) | 0.2 (0.1–0.3) | 0.1 (0.0–0.2) |
| Comorbidities, n (%) | |||
| Hypertension | 1396 (20.2) | 864 (33.1) | 532 (12.3) |
| Stroke | 296 (4.3) | 206 (7.9) | 90 (2.1) |
| Asthma | 966 (14.0) | 576 (22.0) | 390 (9.1) |
| Chronic obstructive pulmonary disease | 334 (4.8) | 246 (9.4) | 88 (2.0) |
| Coronary heart disease | 368 (5.3) | 277 (10.6) | 91 (2.1) |
| Heart failure | 196 (2.8) | 144 (5.5) | 52 (1.2) |
| Type 1 diabetes | 42 (0.6) | 34 (1.3) | 8 (0.2) |
| Type 2 diabetes | 559 (8.1) | 397 (15.2) | 162 (3.8) |
| CKD stage 3–5 | 351 (5.1) | 255 (9.8) | 96 (2.2) |
| Smoking status, n (%) | |||
| Current smoker | 784 (11.3) | 221 (8.5) | 563 (13.1) |
| Ex-smoker | 2171 (31.4) | 974 (37.3) | 1197 (27.8) |
| Never smoked | 3279 (47.4) | 1215 (46.5) | 2064 (47.9) |
| Missing data | 687 (9.9) | 203 (7.8) | 484 (11.2) |
| Body mass index | 27.9 (6.9) | 28.7 (7.4) | 27.4 (6.5) |
| Medication, n (%) | |||
| Antiplatelets | 893 (12.9) | 543 (20.8) | 350 (8.1) |
| Oral anticoagulants | 651 (9.4) | 368 (14.1) | 283 (6.6) |
| ACE inhibitors | 977 (14.1) | 554 (21.2) | 423 (9.8) |
| Angiotensin receptor blockers | 473 (6.8) | 286 (10.9) | 187 (4.3) |
| Diuretics | 1051 (15.2) | 627 (24.0) | 424 (9.8) |
| Calcium channel blockers | 957 (13.8) | 567 (21.7) | 390 (9.1) |
| Beta blockers | 1117 (16.1) | 567 (21.7) | 550 (12.8) |
| Alpha blockers | 141 (2.0) | 95 (3.6) | 46 (1.1) |
| Insulin | 270 (3.9) | 177 (6.8) | 93 (2.2) |
| Diabetic oral agents | 611 (8.8) | 398 (15.2) | 213 (4.9) |
| Lipid-lowering drugs including statins | 1550 (22.4) | 959 (36.7) | 591 (13.7) |
CHIA, Care and Health Information Analytics; CKD, chronic kidney disease; IMD, Index of Multiple Deprivation.