Table 3.
Factors associated with severe clinical outcomes among persons with SARS-CoV-2 infection in Northern California, stratified by time periods of predominant Omicron SARS-CoV-2 variant (December 18, 2021-January 7, 2022, n=48,101) and Delta SARS-CoV-2 variant (July 5, 2021-November 30, 2021, n=69,977) transmission.
| Any Hospitalization |
Hospitalization with low-flow oxygen support |
Hospitalization with high-flow oxygen support or NIPPV |
Hospitalization with invasive mechanical ventilation |
Death |
||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Characteristic | n (%) |
aHR (CI) |
n (%) |
aHR (CI) |
n (%) |
aHR (CI) |
n (%) |
aHR (CI) |
n (%) |
aHR (CI) |
| Time period | ||||||||||
| Delta, July 5, 2021-Nov 30, 2021 |
5,445 (7.8%) |
1.0 | 4,483 (6.4%) |
1.0 | 1,980 (2.8%) |
1.0 | 521 (0.7%) |
1.0 | 398 (0.7%) |
1.0 |
| Omicron, Dec 18, 2021-Jan 7, 2022 |
1,169 (2.4%) |
0.55 (0.51, 0.59) |
773 (1.6%) |
0.46 (0.43, 0.5) |
302 (0.6%) |
0.47 (0.41, 0.54) |
70 (0.1%) |
0.43 (0.33, 0.56) |
83 (0.2%) |
0.54 (0.42, 0.7) |
| Age, years | ||||||||||
| 0-17 | 81 (0.4%) |
0.12 (0.1, 0.16) |
39 (0.2%) |
0.09 (0.07, 0.13) |
16 (0.1%) |
0.13 (0.08, 0.21) |
3 (0.0%) |
0.11 (0.04, 0.37) |
2 (0.0%) |
0.2 (0.05, 0.87) |
| 18-39 | 1,253 (2.9%) |
1.0 | 812 (1.9%) |
1.0 | 285 (0.7%) |
1.0 | 52 (0.1%) |
1.0 | 18 (0.0%) |
1.0 |
| 40-49 | 924 (4.7%) |
1.61 (1.48, 1.76) |
778 (4.0%) |
2.07 (1.87, 2.29) |
360 (1.8%) |
2.69 (2.3, 3.15) |
85 (0.4%) |
3.49 (2.47, 4.95) |
35 (0.2%) |
4.23 (2.36, 7.59) |
| 50-59 | 1,184 (7.4%) |
2.67 (2.46, 2.9) |
1,023 (6.4%) |
3.6 (3.27, 3.97) |
494 (3.1%) |
5 (4.3, 5.81) |
134 (0.8%) |
7.36 (5.3, 10.22) |
74 (0.5%) |
11.2 (6.56, 19.12) |
| 60-69 | 1,225 (11.5%) |
3.94 (3.6, 4.3) |
1,042 (9.8%) |
5.5 (4.97, 6.09) |
521 (4.9%) |
8.23 (7.04, 9.63) |
164 (1.5%) |
13.66 (9.78, 19.06) |
94 (0.9%) |
19.65 (11.51, 33.57) |
| 70-79 | 1,003 (20.2%) |
5.86 (5.27, 6.52) |
831 (16.7%) |
8.32 (7.36, 9.39) |
370 (7.4%) |
11.77 (9.77, 14.19) |
111 (2.2%) |
17.27 (11.75, 25.37) |
133 (2.7%) |
45.8 (26.42, 79.38) |
| 80+ | 954 (40.9%) |
10.99 (9.75, 12.39) |
731 (31.4%) |
15.13 (13.18, 17.37) |
236 (10.1%) |
16.16 (12.96, 20.14) |
42 (1.8%) |
14.16 (8.76, 22.86) |
205 (8.8%) |
127.58 (72.86, 223.39) |
| Sex | ||||||||||
| Female | 3,339 (5.2%) |
1.0 | 2,524 (3.9%) |
1.0 | 964 (1.5%) |
1.0 | 253 (0.4%) |
1.0 | 231 (0.4%) |
1.0 |
| Male | 3,285 (6.1%) |
1.29 (1.23, 1.36) |
2,732 (5.1%) |
1.42 (1.34, 1.5) |
1,318 (2.5%) |
1.84 (1.69, 2.01) |
338 (0.6%) |
1.77 (1.49, 2.09) |
330 (0.6%) |
2.06 (1.73, 2.46) |
| Race/Ethnicity | ||||||||||
| LatinX/Hispanic Ethnicity | 1,756 (5.3%) |
1.24 (1.16, 1.31) |
1,394 (4.2%) |
1.24 (1.16, 1.33) |
620 (1.9%) |
1.36 (1.22, 1.5) |
154 (0.5%) |
1.41 (1.15, 1.72) |
123 (0.4%) |
1.24 (1, 1.53) |
| Black/African Descent | 904 (7.2%) |
1.24 (1.15, 1.34) |
690 (5.5%) |
1.15 (1.06, 1.26) |
273 (2.2%) |
1.06 (0.93, 1.22) |
71 (0.6%) |
1.08 (0.82, 1.41) |
60 (0.5%) |
0.93 (0.7, 1.24) |
| Asian Descent | 670 (3.9%) |
1.54 (1.41, 1.68) |
498 (2.9%) |
1.51 (1.36, 1.67) |
243 (1.4%) |
2.15 (1.86, 2.48) |
63 (0.4%) |
2.26 (1.69, 3) |
52 (0.3%) |
1.62 (1.19, 2.21) |
| White/European or Middle Eastern Descent | 3,036 (6.6%) |
1.0 | 2,468 (5.4%) |
1.0 | 1,034 (2.2%) |
1.0 | 269 (0.6%) |
1.0 | 303 (0.7%) |
1.0 |
| Other/Unknown | 258 (2.8%) |
0.94 (0.82, 1.07) |
206 (2.3%) |
0.94 (0.81, 1.08) |
112 (1.2%) |
1.2 (0.98, 1.46) |
34 (0.4%) |
1.42 (0.99, 2.04) |
23 (0.3%) |
1.38 (0.9, 2.12) |
| Charlson Co-Morbidity Index Score | ||||||||||
| Missing (no visits in prior year) |
431 (4.0%) |
1.28 (1.15, 1.42) |
369 (3.4%) |
1.34 (1.19, 1.5) |
180 (1.7%) |
1.39 (1.18, 1.63) |
62 (0.6%) |
2.23 (1.67, 2.98) |
35 (0.3%) |
2.71 (1.83, 4.03) |
| Score 0 | 2,567 (3.2%) |
1.0 | 1,979 (2.4%) |
1.0 | 860 (1.1%) |
1.0 | 190 (0.2%) |
1.0 | 89 (0.1%) |
1.0 |
| Score 1 | 1,045 (6.9%) |
1.21 (1.1, 1.32) |
846 (5.6%) |
1.09 (0.98, 1.21) |
396 (2.6%) |
1.07 (0.92, 1.25) |
99 (0.7%) |
1.09 (0.8, 1.48) |
77 (0.5%) |
1.81 (1.28, 2.55) |
| Score 2 | 660 (13.9%) |
1.45 (1.29, 1.64) |
543 (11.4%) |
1.29 (1.13, 1.47) |
232 (4.9%) |
1.11 (0.91, 1.36) |
58 (1.2%) |
1.06 (0.71, 1.59) |
64 (1.3%) |
2.07 (1.39, 3.07) |
| Score 3+ | 1,921 (29.7%) |
1.88 (1.61, 2.19) |
1,519 (23.5%) |
1.54 (1.29, 1.84) |
614 (9.5%) |
1.3 (0.99, 1.71) |
182 (2.8%) |
1.62 (0.97, 2.69) |
296 (4.6%) |
3.02 (1.91, 4.76) |
| Chronic obstructive pulmonary disease | 1,421 (11.2%) |
1.13 (1.05, 1.21) |
1,191 (9.4%) |
1.31 (1.21, 1.42) |
512 (4.0%) |
1.39 (1.23, 1.57) |
137 (1.1%) |
1.33 (1.05, 1.69) |
173 (1.4%) |
1.2 (0.98, 1.47) |
| Diabetes | 1,891 (18.3%) |
1.22 (1.13, 1.32) |
1,556 (15.1%) |
1.3 (1.19, 1.42) |
706 (6.8%) |
1.37 (1.2, 1.57) |
208 (2.0%) |
1.48 (1.14, 1.93) |
227 (2.2%) |
1.15 (0.93, 1.43) |
| Atherosclerotic cardiovascular disease | 2,135 (26.2%) |
1.39 (1.27, 1.51) |
1,684 (20.7%) |
1.34 (1.22, 1.49) |
669 (8.2%) |
1.26 (1.09, 1.47) |
193 (2.4%) |
1.47 (1.11, 1.95) |
314 (3.9%) |
1.14 (0.88, 1.47) |
| Renal disease | 1,265 (33.1%) |
1.44 (1.31, 1.58) |
990 (25.9%) |
1.43 (1.29, 1.59) |
398 (10.4%) |
1.44 (1.23, 1.7) |
113 (3.0%) |
1.41 (1.04, 1.89) |
201 (5.3%) |
1.39 (1.09, 1.76) |
| Cancer | 408 (21.1%) |
1.26 (1.13, 1.41) |
320 (16.5%) |
1.3 (1.14, 1.48) |
133 (6.9%) |
1.36 (1.11, 1.66) |
36 (1.9%) |
1.24 (0.85, 1.81) |
72 (3.7%) |
1.62 (1.23, 2.14) |
| Rheumatologic disease | 166 (17.1%) |
1.21 (1.03, 1.41) |
146 (15.0%) |
1.37 (1.16, 1.63) |
58 (6.0%) |
1.41 (1.08, 1.85) |
14 (1.4%) |
1.18 (0.68, 2.04) |
19 (2.0%) |
1.18 (0.74, 1.89) |
| Dementia | 346 (57.8%) |
2.01 (1.78, 2.27) |
250 (41.7%) |
1.74 (1.5, 2) |
76 (12.7%) |
1.32 (1.02, 1.7) |
13 (2.2%) |
0.95 (0.53, 1.7) |
74 (12.4%) |
1.91 (1.45, 2.51) |
| Body mass index | ||||||||||
| <25 | 1,268 (3.6%) |
1.0 | 896 (2.5%) |
1.0 | 308 (0.9%) |
1.0 | 85 (0.2%) |
1.0 | 156 (0.4%) |
1.0 |
| 25-29.9 | 1,797 (5.7%) |
1.09 (1.01, 1.18) |
1,388 (4.4%) |
1.17 (1.07, 1.27) |
556 (1.8%) |
1.28 (1.11, 1.48) |
123 (0.4%) |
0.91 (0.69, 1.21) |
141 (0.5%) |
0.78 (0.62, 0.99) |
| 30-34.9 | 1,626 (7.5%) |
1.39 (1.29, 1.5) |
1,348 (6.2%) |
1.56 (1.43, 1.71) |
604 (2.8%) |
1.94 (1.68, 2.25) |
147 (0.7%) |
1.48 (1.12, 1.96) |
116 (0.5%) |
1.07 (0.82, 1.38) |
| 35-39.9 | 889 (8.6%) |
1.7 (1.55, 1.86) |
752 (7.3%) |
1.98 (1.79, 2.2) |
360 (3.5%) |
2.68 (2.28, 3.14) |
102 (1.0%) |
2.39 (1.77, 3.23) |
72 (0.7%) |
1.59 (1.18, 2.14) |
| >=40 | 998 (11.9%) |
2.54 (2.32, 2.78) |
837 (10.0%) |
2.96 (2.67, 3.28) |
444 (5.3%) |
4.53 (3.87, 5.31) |
134 (1.6%) |
4.11 (3.06, 5.51) |
73 (0.9%) |
2.37 (1.74, 3.22) |
| COVID-19 vaccination | ||||||||||
| None | 4,237 (8.5%) |
8.34 (7.25, 9.6) |
3,582 (7.2%) |
9.88 (8.3, 11.76) |
1,684 (3.4%) |
13.71 (10.2, 18.42) |
463 (0.9%) |
11.65 (6.78, 20.02) |
366 (0.7%) |
12.18 (7.32, 20.26) |
| Complete primary series | 1,914 (3.7%) |
1.72 (1.49, 1.97) |
1,343 (2.6%) |
1.63 (1.37, 1.95) |
473 (0.9%) |
1.75 (1.29, 2.36) |
97 (0.2%) |
1.1 (0.63, 1.93) |
152 (0.3%) |
1.82 (1.08, 3.06) |
| Completed primary series + additional dose | 248 (2.1%) |
1.0 | 162 (1.4%) |
1.0 | 53 (0.4%) |
1.0 | 16 (0.1%) |
1.0 | 18 (0.2%) |
1.0 |
| Other (partial/mixed/other) |
225 (5.5%) |
3.63 (3.01, 4.38) |
169 (4.1%) |
3.86 (3.08, 4.84) |
72 (1.8%) |
4.75 (3.28, 6.89) |
15 (0.4%) |
3.14 (1.51, 6.52) |
25 (0.6%) |
6.21 (3.3, 11.67) |
| Prior SARS-CoV-2 infection | 149 (4.3%) |
1 (0.85, 1.18) |
76 (2.2%) |
0.67 (0.53, 0.84) |
21 (0.6%) |
0.4 (0.26, 0.61) |
3 (0.1%) |
0.23 (0.07, 0.7) |
10 (0.3%) |
0.72 (0.38, 1.36) |
| Anti-SARS-CoV-2 antibody outpatient treatment | 74 (6.5%) |
0.33 (0.26, 0.41) |
58 (5.1%) |
0.31 (0.24, 0.41) |
15 (1.3%) |
0.21 (0.13, 0.35) |
1 (0.1%) |
0.05 (0.01, 0.37) |
1 (0.1%) |
0.04 (0.01, 0.31) |
aHR = adjusted hazard ratio using cox proportional hazards models to assess the association between SARS-CoV-2 infection during a period with predominant Omicron variant circulation versus predominant Delta variant circulation adjusted for demographics, clinical comorbidities and vaccination status.
*Treatment with bamlanivimab plus etesevimab, casirivimab plus imdevimab, or sotrovimab as an outpatient.
Abbreviations: NIPPV = Non-invasive positive pressure mechanical ventilation.