Table 2 Description of pairs of index cases and related controls and factors associated with the risk of SARS-CoV-2 infection within the household in a household-matched conditional logistic regression analysis
Index cases | Related controls | Univariable analysis | Multivariable analysis | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
Model with variable selection including isolation overall only | Model with variable selection including specific mitigation measures | Model without variable selection and including specific mitigation measures | ||||||||
n = 611 | n = 611 | Odds ratio | 95% CI | Odds ratio | 95% CI | Odds ratio | 95% CI | Odds ratio | 95% CI | |
Age, median [interquartile range] (years) | 44 [40–49] | 45 [40–50] | ||||||||
18–39 years | 143 (23.4%) | 146 (23.9%) | 1 | - | 1 | - | 1 | - | 1 | - |
40–59 years | 448 (73.3%) | 438 (71.7%) | 1.1 | 0.7–1.8 | 1.5 | 0.9–2.5 | 1.5 | 0.9–2.5 | 1.4 | 0.8–2.5 |
≥ 60 years | 20 (3.3%) | 27 (4.4%) | 0.5 | 0.2–1.5 | 1.2 | 0.4–3.7 | 1.2 | 0.4–3.8 | 1.2 | 0.4–3.7 |
Female | 394 (64.5%) | 219 (35.8%) | 1.8 | 1.5–2.1 | 1.9 | 1.5–2.2 | 1.9 | 1.5–2.2 | 1.9 | 1.6–2.3 |
Vaccination status | ||||||||||
Unvaccinated | 181 (29.6%) | 171 (28.0%) | 1 | - | 1 | - | 1 | - | 1 | - |
1 dose | 15 (2.5%) | 20 (3.3%) | 0.4 | 0.1–1.1 | 0.6 | 0.2–1.7 | 0.6 | 0.2–1.7 | 0.6 | 0.2–1.8 |
2 doses | 195 (31.9%) | 161 (26.4%) | 0.5 | 0.2–1.2 | 0.5 | 0.2–1.4 | 0.5 | 0.2–1.4 | 0.5 | 0.2–1.3 |
3–4 dosesa | 220 (36.0%) | 259 (42.4%) | 0.2 | 0.1–0.4 | 0.1 | 0.04–0.4 | 0.1 | 0.04–0.3 | 0.1 | 0.04–0.3 |
History of prior SARS-CoV-2 infection | 26 (4.3%) | 52 (8.5%) | 0.2 | 0.1–0.5 | 0.1 | 0.1–0.3 | 0.1 | 0.1–0.3 | 0.1 | 0.1–0.3 |
Underlying conditions | ||||||||||
Chronic respiratory disease | 33 (5.4%) | 40 (6.6%) | 0.8 | 0.5–1.3 | - | - | - | - | 0.8 | 0.4–1.3 |
Hypertension | 50 (8.2%) | 44 (7.2%) | 1.2 | 0.7–1.8 | - | - | - | - | 1.7 | 1.0–2.8 |
Diabetes mellitus | 5 (0.8%) | 14 (2.3%) | 0.3 | 0.1–0.9 | - | - | - | - | 0.4 | 0.1–1.2 |
Coronary artery disease | 4 (0.7%) | 4 (0.7%) | 1 | 0.3–4.0 | - | - | - | - | 1.8 | 0.4–7.7 |
Isolation from the source case | ||||||||||
Isolation overall | 347 (56.8%) | 378 (61.9%) | 0.6 | 0.4–0.8 | 0.6 | 0.4–0.97 | - | - | - | - |
Specific mitigation measures | ||||||||||
Ventilation of indoor areas | 321 (52.5%) | 350 (57.3%) | 0.6 | 0.4–0.9 | - | - | 0.6 | 0.4–0.9 | 0.5 | 0.3–0.9 |
Mask-wearing | 305 (49.9%) | 318 (52.1%) | 0.8 | 0.5–1.1 | - | - | - | - | 1.0 | 0.6–1.8 |
Surface disinfection | 258 (42.2%) | 255 (41.7%) | 1.1 | 0.7–1.5 | - | - | - | - | 1.6 | 1.0–2.6 |
Separate bathrooms | 165 (27.0%) | 176 (28.8%) | 0.8 | 0.5–1.2 | - | - | - | - | 0.9 | 0.6–1.5 |
Separate meals | 274 (44.8%) | 279 (45.7%) | 0.9 | 0.5–1.4 | - | - | - | - | 1.2 | 0.6–2.2 |