Table 4.
Total Numbers of Cases and Controls, Percentage of Children Vaccinated, and Vaccine Effectiveness for Each Vaccination Period
| Cases |
Controls |
|||||
| Intervention | n | % vaccinated | n | % vaccinated | VEa | 95% CI |
| Routine | 54 | 13.0 | 170 | 73.5 | 96.4 | (88.0–98.9) |
| Routine + October 2008 | 361 | 8.6 | 870 | 80.7 | 97.7 | (95.9–98.7) |
| Routine + October 2008 + January 2009 | 72 | 44.4 | 240 | 94.2 | 94.2 | (86.7–97.4) |
NOTE. VE, vaccine effectiveness; 95% CI, 95% confidence interval.
a
Vaccine effectiveness: adjustment was performed using a conditional logistic regression matched by age and residency place and adjusted by sex.