Table 2.
Characteristics of persons hospitalized after SARS-CoV-2 infection in Northern California stratified by time periods of predominant Omicron SARS-CoV-2 variant (December 18, 2021-January 7, 2022) and Delta SARS-CoV-2 variant (July 5, 2021-November 30, 2021) transmission.
| Characteristic | All, N = 6,624 n (%) |
Omicron period, N = 1,169 n (%) |
Delta period, N = 5,455 n (%) |
p-value2 |
|---|---|---|---|---|
| Age, years1 | 59 (43, 72) | 62 (42, 76) | 58 (44, 72) | <0.001 |
| Age, years | <0.001 | |||
| 0-17 | 81 (1.2%) | 24 (2.1%) | 57 (1.0%) | |
| 18-39 | 1,253 (19%) | 244 (21%) | 1,009 (18%) | |
| 40-49 | 924 (14%) | 108 (9.2%) | 816 (15%) | |
| 50-59 | 1,184 (18%) | 159 (14%) | 1,025 (19%) | |
| 60-69 | 1,225 (18%) | 220 (19%) | 1,005 (18%) | |
| 70-79 | 1,003 (15%) | 175 (15%) | 828 (15%) | |
| 80+ | 954 (14%) | 239 (20%) | 715 (13%) | |
| Sex | 0.064 | |||
| Female | 3,339 (50%) | 618 (53%) | 2,721 (50%) | |
| Male | 3,285 (50%) | 551 (47%) | 2,734 (50%) | |
| Race/Ethnicity | <0.001 | |||
| LatinX/Hispanic Ethnicity | 1,756 (27%) | 266 (23%) | 1,490 (27%) | |
| Black/African Descent | 904 (14%) | 181 (15%) | 723 (13%) | |
| Asian Descent | 670 (10%) | 171 (15%) | 499 (9.1%) | |
| White/European or Middle Eastern Descent | 3,036 (46%) | 508 (43%) | 2,528 (46%) | |
| Other/Unknown | 258 (3.9%) | 43 (3.7%) | 215 (3.9%) | |
| Charlson co-morbidity index scores | <0.001 | |||
| Missing (no visits in prior year) | 431 (6.5%) | 56 (4.8%) | 375 (6.9%) | |
| Score 0 | 2,567 (39%) | 375 (32%) | 2,192 (40%) | |
| Score 1 | 1,045 (16%) | 165 (14%) | 880 (16%) | |
| Score 2 | 660 (10.0%) | 113 (9.7%) | 547 (10%) | |
| Score 3+ | 1,921 (29%) | 460 (39%) | 1,461 (27%) | |
| Chronic obstructive pulmonary disease | 1,421 (21%) | 297 (25%) | 1,124 (21%) | <0.001 |
| Diabetes | 1,891 (29%) | 390 (33%) | 1,501 (28%) | <0.001 |
| Atherosclerotic cardiovascular disease | 2,135 (32%) | 484 (41%) | 1,651 (30%) | <0.001 |
| Renal disease | 1,265 (19%) | 311 (27%) | 954 (17%) | <0.001 |
| Cancer | 408 (6.2%) | 83 (7.1%) | 325 (6.0%) | 0.14 |
| Rheumatologic disease | 166 (2.5%) | 33 (2.8%) | 133 (2.4%) | 0.4 |
| Dementia | 346 (5.2%) | 93 (8.0%) | 253 (4.6%) | <0.001 |
| Body mass index, kg/m2 | <0.001 | |||
| <25 | 1,268 (19%) | 282 (24%) | 986 (18%) | |
| 25-29.9 | 1,797 (27%) | 311 (27%) | 1,486 (27%) | |
| 30-34.9 | 1,626 (25%) | 262 (23%) | 1,364 (25%) | |
| 35-39.9 | 889 (14%) | 136 (12%) | 753 (14%) | |
| ≥40 | 998 (15%) | 167 (14%) | 831 (15%) | |
| COVID-19 vaccination | <0.001 | |||
| None | 4,237 (64%) | 472 (40%) | 3,765 (69%) | |
| Complete primary series | 1,914 (29%) | 476 (41%) | 1,438 (26%) | |
| Completed primary series + additional dose | 248 (3.7%) | 184 (16%) | 64 (1.2%) | |
| Other (partial/mixed/other) | 225 (3.4%) | 37 (3.2%) | 188 (3.4%) | |
| Prior SARS-CoV-2 infection | 149 (2.2%) | 52 (4.4%) | 97 (1.8%) | <0.001 |
| Anti-SARS-CoV-2 antibody outpatient treatment3 | 74 (1.1%) | 14 (1.2%) | 60 (1.1%) | 0.8 |
| Severe clinical outcomes | ||||
| Hospitalized with low flow oxygen support | 5,256 (79%) | 773 (66%) | 4,483 (82%) | <0.001 |
| Hospitalized with high flow oxygen support or non-invasive mechanical ventilation | 2,282 (34%) | 302 (26%) | 1,980 (36%) | <0.001 |
| Hospitalized with invasive mechanical ventilation | 591 (8.9%) | 70 (6.0%) | 521 (9.6%) | <0.001 |
| Died | 473 (7.1%) | 75 (6.4%) | 398 (7.3%) | 0.3 |
| Receipt of COVID-19 treatment | ||||
| Remdesivir | 4,701 (71%) | 662 (57%) | 4,039 (74%) | <0.001 |
| Dexamethasone | 5,056 (76%) | 667 (57%) | 4,389 (80%) | <0.001 |
| Tocilizumab | 1,017 (15%) | 153 (13%) | 864 (16%) | 0.018 |
1
Median (IQR); n (%).
2
Wilcoxon rank sum test; Pearson's Chi-squared test.
3
Treatment with bamlanivimab plus etesevimab, casirivimab plus imdevimab, or sotrovimab.