Table 5.
Comparison of the Omicron infection with the Delta infection according to vaccination status: demographics, underlying diseases, and presentation
| Vaccinated (N = 1220) |
Unvaccinated (N = 950) |
|||||
|---|---|---|---|---|---|---|
| Omicron (n = 746) | Delta (n = 474) | p | Omicron (n = 469) | Delta (n = 481) | p | |
| Age (y), n (%) | 0.031 | <0.001 | ||||
| <35 y | 67 (9.0) | 27 (5.7) | 54 (11.6) | 97 (20.2) | ||
| 35–65 y | 198 (26.6) | 111 (23.4) | 128 (27.4) | 225 (46.8) | ||
| >65 y | 481 (64.5) | 336 (70.9) | 287 (61.2) | 159 (33.1) | ||
| Age (y) | 74.0 [57.3 85.0] | 75.0 [63.3-84.0] | 0.012 | 71.0 [55.0-83.0] | 55.0 [38.0-73.0] | <0.001 |
| Sex: men, n (%) | 406 (54.4) | 261 (55.1) | 0.873 | 217 (46.3) | 223 (46.4) | 1.000 |
| BMI (kg/m2) | 25.9 [22.2-29.4] | 25.8 [22.3-31.1] | 0.036 | 26.1 [22.6-29.2] | 27.2 [24.2-31.2] | <0.001 |
| Overweight (BMI > 25), n (%) | 221 (56.5) | 192 (56.6) | 1.000 | 134 (57.8) | 222 (69.4) | 0.006 |
| Pre-existing comorbidities, n (%) | ||||||
| Cardiac failure | 121 (23.6) | 50 (13.7) | <0.001 | 65 (18.3) | 29 (8.0) | <0.001 |
| Respiratory disease | 103 (13.8) | 91 (20.7) | 0.002 | 47 (10.0) | 54 (12.6) | 0.256 |
| Oxygen at home | 15 (2.9) | 14 (4.0) | 0.515 | 3 (0.8) | 5 (1.4) | 0.501 |
| Kidney failure (GFR < 30) | 88 (12.0) | 51 (15.2) | 0.182 | 31 (6.8) | 10 (3.2) | 0.041 |
| Diabetes | 184 (24.7) | 127 (28.7) | 0.141 | 106 (22.6) | 76 (17.8) | 0.086 |
| Hypertension | 261 (50.8) | 244 (55.1) | 0.206 | 183 (51.5) | 123 (28.7) | <0.001 |
| Solid cancer for <3 mo | 22 (3.0) | 17 (4.8) | 0.170 | 9 (1.9) | 8 (2.2) | 0.945 |
| Haematologic malignancy | 42 (5.6) | 25 (7.1) | 0.428 | 10 (2.1) | 6 (1.7) | 0.869 |
| Immunodepression | 77 (15.0) | 74 (20.3) | 0.048 | 33 (9.3) | 21 (5.8) | 0.110 |
| At least one comorbidity among those above | 523 (70.1) | 369 (90.4) | <0.001 | 330 (70.4) | 306 (86.9) | <0.001 |
| Number of comorbidities | 1.0 [0.0-2.0] | 2.0 [1.0-3.0] | <0.001 | 1.0 [0.0-2.0] | 1.0 [0.0-2.0] | 0.010 |
| Tobacco, active or discontinued < 3 y, n (%) | 44 (11.9) | 36 (10.3) | 0.580 | 38 (15.4) | 49 (14.3) | 0.800 |
| Previous SARS-CoV-2 infection, n (%) | 12 (1.9) | 19 (5.4) | 0.005 | 10 (2.4) | 12 (3.4) | 0.533 |
| Time from a previous infection (d) | 319.0 [43.0-344.0] | 226.0 [176.5-299.0] | 0.688 | 215.0 [97.3-389.5] | 69 [43.3-244.3] | 0.113 |
| Time from last vaccine dose (d)a | 113.0 [64.0-178.2] | 125.0 [82.0-166.5] | 0.716 | – | – | – |
| Admission for COVID-19 | 359 (48.7) | 281 (59.3) | <0.001 | 317 (69.5) | 361 (75.1) | 0.069 |
| Ct value (lowest value if many) | 21.4 [18.2-27.0] | 26.0 [18.0-34.0] | <0.001 | 22.1 [19.0-27.3] | 26.0 [21.0-33.0] | <0.001 |
| CRP (highest value) (mg/L) | 58.0 [21.5-117.5] | 87.5 [31.3-152.8] | <0.001 | 66.0 [26.0-126.3] | 86.0 [34.0-145.0] | 0.073 |
| The proportion of lungs involved on CT scan n (%) | 0.134 | <0.001 | ||||
| 0–10% | 90 (50.3) | 67 (36.8) | 51 (30.4) | 31 (13.5) | ||
| 11–25% | 40 (22.3) | 50 (27.5) | 55 (32.7) | 57 (24.9) | ||
| 26–50% | 32 (17.9) | 39 (21.4) | 41 (24.4) | 75 (32.8) | ||
| 51–75% | 12 (6.7) | 18 (9.9) | 18 (10.7) | 49 (21.4) | ||
| >75% | 5 (2.8) | 8 (4.4) | 3 (1.8) | 17 (7.4) | ||
BMI, body mass index; GFR, glomerular filtration rate; Ct, Cycle threshold; CT, computed tomography; CRP, C-reactive protein.
a
For the time from the last infection and from the last vaccine injection.