Age group | Intervention systems | Non-intervention systems | Relative risk | Lower 95% CI | Upper 95% CI | ||
---|---|---|---|---|---|---|---|
N | Attack rate (%) | N | Attack rate (%) | ||||
All ages | 1291 | 2.5 | 1211 | 3.6 | 0.588 | 0.291 | 1.186 |
< 5 years | 61 | 3.3 | 70 | 8.6 | 0.382 | 0.077 | 1.895 |
5 to 15 years | 202 | 3.0 | 200 | 4.5 | 0.657 | 0.228 | 1.891 |
> 15 years | 1025 | 2.3 | 972 | 2.9 | 0.687 | 0.317 | 1.483 |