Volume 20, Number 7—July 2014
Dispatch
Rates of Influenza-like Illness and Winter School Breaks, Chile, 2004–2010
, Sherry Towers, Cécile Viboud, Rodrigo Fuentes, and Viviana Sotomayor
Table 2
ILI incidence rate ratios for schoolchildren-to-adult age groups during 6-week periods surrounding school winter breaks, Chile, 2004–2010*
| Age group, y | ILI incidence rate ratio |
p value |
||||
|---|---|---|---|---|---|---|
| Before school break | During school break | After school break | Before break vs. during break† | During break vs. after break‡ | ||
| Adults >20 | ||||||
| Schoolchildren 5–14 | 2.59 (0.14) | 1.28 (0.16) | 1.98 (0.10) | <0.001 | <0.001 | |
| Schoolchildren 15–19 | 2.02 (0.07) | 1.22 (0.04) | 1.66 (0.07) | <0.001 | <0.001 | |
| Schoolchildren 5–19 |
2.40 (0.11) |
1.26 (0.11) |
1.87 (0.07) |
<0.001 |
<0.001 |
|
| Adults 20–64 | ||||||
| Schoolchildren 5–14 | 2.52 (0.11) | 1.25 (0.16) | 2.00 (0.10) | <0.001 | <0.001 | |
| Schoolchildren 15–19 | 1.97 (0.05) | 1.18 (0.04) | 1.68 (0.07) | <0.001 | <0.001 | |
| Schoolchildren 5–19 |
2.33 (0.08) |
1.23 (0.11) |
1.89 (0.08) |
<0.001 |
<0.001 |
|
| Adults >65 | ||||||
| Schoolchildren 5–14 | 3.82 (0.62) | 1.61 (0.23) | 1.85 (0.14) | <0.001 | 0.187 | |
| Schoolchildren 15–19 | 2.94 (0.46) | 1.52 (0.08) | 1.56 (0.11) | 0.001 | 0.401 | |
| Schoolchildren 5–19 | 3.52 (0.56) | 1.58 (0.16) | 1.75 (0.12) | <0.001 | 0.206 | |
*The “after break” period begins 2 weeks after the winter break ends because the reduction in the incidence rate ratio during the winter break was maintained on average for 2 weeks after the end of the winter break. ILI, influenza-like illness.
†p value of a 1-sided Z test comparing the average incidence rate ratio (ratio of incidence rate for schoolchildren to incidence rate for adults) during the 2-week period before the school break to that during the winter break. Small p values indicate that the incidence rate ratio for the period before the break is significantly higher than that for the period during the break; p values near 1.00 indicate that the incidence rate ratio for the period before the break is significantly lower than that for during the break.
‡p value of a 1-sided Z test comparing the average incidence rate ratio during the 2-week period after the school break to that during the winter break period. Small p values indicate that the incidence rate ratio for the period after the winter break period is significantly higher than that for the period during the winter break; p values near 1.00 indicate that the incidence rate ratio for the period after the break is significantly lower than that for the period during the break.