Table 2.
Characteristics of study participants in the vaccine effectiveness analysis 24–36 months after vaccination (study period 2)
| Case group | Control group | p value | Standardised mean difference | ||
|---|---|---|---|---|---|
| Age group at vaccination | .. | .. | .. | 0·179 | |
| 1–4 years | 60/402 (14·9%) | 235/1450 (16·2%) | Ref | .. | |
| 5–9 years | 109/402 (27·1%) | 292/1450 (20·1%) | 0·056 | .. | |
| 10–19 years | 90/402 (22·4%) | 376/1450 (25·9%) | 0·30 | .. | |
| 20–39 years | 67/402 (16·7%) | 283/1450 (19·5%) | 0·074 | .. | |
| 40–59 years | 55/402 (13·7%) | 190/1450 (13·1%) | 0·43 | .. | |
| ≥60 years | 21/402 (5·2%) | 74/1450 (5·1%) | 0·44 | .. | |
| Sex | .. | .. | .. | 0·005 | |
| Female | 215/402 (53·5%) | 772/1450 (53·2%) | Ref | .. | |
| Male | 187/402 (46·5%) | 678/1450 (46·8%) | 0·95 | .. | |
| Educational attainment* | .. | .. | .. | 0·353 | |
| None or primary | 52/126 (41·3%) | 138/542 (25·5%) | Ref | .. | |
| Lower secondary | 21/126 (16·7%) | 98/542 (18·1%) | 0·028 | .. | |
| Upper secondary | 46/126 (36·5%) | 273/542 (50·4%) | 0·0008 | .. | |
| Bachelor or higher | 7/126 (5·6%) | 33/542 (6·1%) | 0·35 | .. | |
| Occupation | .. | .. | .. | 0·113 | |
| No work | 71/402 (17·7%) | 218/1450 (15·0%) | Ref | .. | |
| Children younger than school age | 45/402 (11·2%) | 152/1450 (10·5%) | 0·58 | .. | |
| Students | 180/402 (44·8%) | 642/1450 (44·3%) | 0·71 | .. | |
| Informal work | 92/402 (22·9%) | 363/1450 (25·0%) | 0·15 | .. | |
| Salaried | 14/402 (3·5%) | 74/1450 (5·1%) | 0·043 | .. | |
| Missing | 0/402 | 1/1450 (<0·1%) | .. | .. | |
| Household size | 7·0 (5·0 to 9·0) | 7·0 (6·0 to 9·0) | 0·3607 | 0·075 | |
| Drinking water source | .. | .. | .. | 0·033 | |
| Improved | 220/402 (54·7%) | 817/1450 (56·3%) | Ref | .. | |
| Unimproved | 182/402 (45·3%) | 632/1450 (43·6%) | 0·46 | .. | |
| Missing | 0/402 | 1/1450 (<0·1%) | .. | .. | |
| Living in household with shared toilet | .. | .. | .. | 0·154 | |
| Private | 159/402 (39·6%) | 684/1450 (47·2%) | Ref | .. | |
| Shared | 243/402 (60·5%) | 766/1450 (52·8%) | 0·0049 | .. | |
| Toilet type | .. | .. | .. | 0·085 | |
| Improved | 262/402 (65·2%) | 1003/1450 (69·2%) | Ref | .. | |
| Unimproved | 140/402 (34·8%) | 447/1450 (30·8%) | 0·11 | .. | |
| Soap and water available for handwashing | 217/402 (54·0%) | 664/1450 (45·8%) | <0·0001 | 0·164 | |
| Living in household with electricity | 150/402 (37·3%) | 632/1450 (43·6%) | 0·0090 | 0·128 | |
| Wealth index† | −5·3 (−50·0 to 31·3) | 2·7 (−30·9 to 36·5) | 0·0001 | 0·182 | |
| Vaccination status | .. | .. | .. | 0·244 | |
| Not vaccinated | 275/402 (68·4%) | 850/1450 (58·6%) | Ref | .. | |
| One dose | 81/402 (20·2%) | 444/1450 (30·6%) | <0·0001 | .. | |
| Two doses | 46/402 (11·4%) | 156/1450 (10·8%) | 0·39 | .. | |
| Vaccination card available (for those who were vaccinated) | 22/123 (17·9%) | 80/599 (13·4%) | 0·025 | 0·125 | |
Data are n/N (%) or median (IQR) unless otherwise specified. The distribution of age and sex for the case group and control group does not match perfectly because the number of individuals in the control group included for each individual in the case group varied slightly due to enrolled participants in the control group either not meeting the eligibility criteria (eg, not living in Uvira during vaccination) or not recalling their vaccination status. p values were obtained from univariable conditional logistic regression models.
The question about education attainment was only asked to individuals aged ≥18 years.
Wealth index was multiplied by 100. The higher the wealth index the richer the household.