Table 3. Overall vaccine effectiveness against cholera using ring vaccination strategy, by age group of the index case.
| Duration of Follow-Up | High Vaccine Coverage Cohorts* (Coverage ≥ 30%) | Low Vaccine Coverage Cohorts* (Coverage ≤ 12%) | Vaccine Effectiveness (95% CI; p-Value) | |||
|---|---|---|---|---|---|---|
| Population † | Number of Cases ‡ | Population † | Number of Cases ‡ | Crude | Adjusted £ | |
| Age group: <5 y | ||||||
| 2 y | 1,752 | 0 | 1,848 | 12 | 100% | ** |
| 3 y | 3,607 | 2 | 3,396 | 15 | 88% (45 to 97; 0.0058) | 86% (39 to 97; 0.0095) |
| 4 y | 4,978 | 7 | 5,166 | 18 | 60% (4 to 83; 0.0414) | 56% (−9 to 82; 0.0776) |
| 5 y | 5,611 | 7 | 5,649 | 18 | 61% (4 to 84; 0.0351) | 57% (−7 to 83; 0.0684) |
| Age group: ≥5 y | ||||||
| 2 y | 20,592 | 2 | 19,406 | 10 | 81% (14 to 96; 0.0312) | ** |
| 3 y | 42,452 | 5 | 36,984 | 14 | 69% (14 to 89; 0.0250) | 66% (5 to 88; 0.0402) |
| 4 y | 59,317 | 10 | 57,121 | 26 | 63% (23 to 88; 0.0076) | 66% (27 to 84; 0.0059) |
| 5 y | 67,367 | 11 | 63,141 | 26 | 60% (20 to 80; 0.0101) | 65% (26 to 84; 0.0064) |
*The vaccine coverage of individuals living within 25 m of index cases was calculated as the number of two-dose vaccine recipients divided by all population within 25 m.
†Cumulative total population within 25 m of the index cases.
‡Cumulative total cholera cases within 25 m of the index cases (excluding index cases) and within 8–28 d of onset of index cases.
£Adjusted for distance from household to nearest water body.
**Not enough cases to develop a multivariable model.