Table 1.
Descriptive statistics of study population, stratified according to vaccination status before covid-19 infection. Values are number (percentage) unless stated otherwise
| Vaccination status pre-covid-19 | Standardised mean difference | ||
|---|---|---|---|
| Not vaccinated (n=290 030) | Vaccinated (n=299 692) | ||
| Sex: | 0.10 | ||
| Men | 142 921 (49.3) | 132 650 (44.3) | |
| Women | 147 109 (50.7) | 167 042 (56.7) | |
| Median (IQR) age (years)* | 39 (29-50) | 42 (32-53) | 0.20 |
| Age group* (years): | 0.19 | ||
| 18-34 | 118 365 (40.8) | 99 664 (33.3) | |
| 35-44 | 66 840 (23.0) | 73 285 (24.5) | |
| 45-54 | 55 279 (19.1) | 60 790 (20.3) | |
| 55-64 | 32 001 (11.0) | 37 324 (12.5) | |
| ≥65 | 17 545 (6.0) | 28 629 (9.6) | |
| Region of birth: | 0.23 | ||
| Africa | 10 121 (3.5) | 6498 (2.2) | |
| Asia and Oceania | 37 697 (13.0) | 26 980 (9.0) | |
| Europe† | 21 493 (7.4) | 15 323 (5.1) | |
| North and South America | 6683 (2.3) | 6269 (2.1) | |
| Sweden | 196 490 (67.7) | 232 860 (77.7) | |
| Unknown | 17 546 (6.0) | 11 762 (3.9) | |
| Education: | 0.23 | ||
| Primary school (<10 years) | 44 093 (15.2) | 31 835 (10.6) | |
| Secondary school (10-12 years) | 118 613 (40.9) | 108 470 (36.2) | |
| Tertiary school (>12 years) | 116 232 (40.1) | 152 126 (50.8) | |
| Unknown | 11 092 (3.8) | 7261 (2.4) | |
| Employment status: | 0.05 | ||
| Employed | 248 127 (85.6) | 260 318 (86.9) | |
| Unemployed | 37 847 (13.0) | 36 621 (12.2) | |
| Unknown | 4056 (1.4) | 2753 (0.9) | |
| Comorbidities‡: | |||
| Diabetes | 9388 (3.2) | 11 449 (3.8) | 0.03 |
| Cardiovascular disease | 42 684 (14.7) | 54 491 (18.2) | 0.09 |
| Respiratory disease | 21 807 (7.5) | 25 055 (8.4) | 0.03 |
| Psychiatric disease | 81 807 (28.2) | 86 841 (29.0) | 0.02 |
| No of healthcare contacts in 2019: | 0.07 | ||
| 0 | 63 866 (22.0) | 60 305 (20.1) | |
| 1-3 | 85 699 (29.5) | 87 623 (29.2) | |
| 4-10 | 76 135 (26.3) | 81 056 (27.0) | |
| >10 | 51 609 (17.8) | 58 983 (19.7) | |
| Unknown | 12 721 (4.4) | 11 725 (3.9) | |
| No of vaccine doses before covid-19: | |||
| 1 | - | 21 111 (7.0) | |
| 2 | - | 205 650 (68.6) | |
| 3 | - | 72 843 (24.3) | |
| 4 | - | 83 (<0.1) | |
| 5 | - | 5 (<0.1) | |
| Severity of covid-19: | 0.15 | ||
| Admitted to hospital, ICU | 389 (0.1) | 77 (<0.1) | |
| Admitted to hospital, not ICU | 11 178 (3.9) | 4610 (1.5) | |
| Not admitted to hospital | 278 463 (96.0) | 295 005 (98.4) | |
| Predominant variant during acute infection§: | 2.4 | ||
| Pre-alpha | 53 021 (18.3) | 405 (0.1) | |
| Alpha | 174 689 (60.2) | 10 394 (3.5) | |
| Delta | 26 260 (9.1) | 64 563 (21.5) | |
| Omicron | 36 060 (12.4) | 224 330 (74.9) | |
ICD-10=international classification of diseases, 10th revision;.ICU=intensive care unit; IQR=interquartile range.
Study population included all adult (≥18 years) residents in the two largest regions of Sweden with covid-19 first registered during the study inclusion period, 27 December 2020 to 9 February 2022.
Age at study start, 27 December 2020.
Not including Sweden.
Comorbidities registered with ICD-10 diagnosis codes in specialist inpatient and outpatient healthcare registers and regional primary healthcare databases during 2015-19: diabetes (E10-E11), cardiovascular disease (I00-I99), respiratory disease (J40-J99), and psychiatric disease (F00-F99).
In Sweden, pre-alpha variants predominated from February 2020 to January 2021, followed by alpha from February 2021 to June 2021, delta from July 2021 to December 2021, and omicron from January 2022 and until end of inclusion 9 February 2022.