ILI IRRs of schoolchildren to adults during 2-week periods surrounding winter/summer breaks, by age group, Beijing, 2008–2015
| ILI IRR (95% CI) | p Value* | ||||
|---|---|---|---|---|---|
| Age group | Before school break | During school break | After school break | Before to during | During to after |
| Winter | |||||
| 5–14 | |||||
| 25–59 | 7.26 (6.99 to 7.53) | 9.95 (9.61 to 10.3) | 13.6 (12.9 to 14.4) | <0.001 | <0.001 |
| ≥60 | 8.02 (7.50 to 8.58) | 9.20 (8.67 to 9.76) | 13.3 (12.1 to 14.7) | 0.003 | <0.001 |
| 15–25 | |||||
| 25–59 | 1.12 (1.06 to 1.19) | 1.03 (0.98 to 1.09) | 1.33 (1.22 to 1.45) | 0.04 | <0.001 |
| ≥60 | 1.24 (1.14 to 1.34) | 0.96 (0.89 to 1.03) | 1.30 (1.16 to 1.47) | <0.001 | <0.001 |
| Summer | |||||
| 5–14 | |||||
| 25–59 | 21.6 (20.2 to 23.0) | 17.0 (16.5 to 17.6) | 20.7 (19.4 to 22.1) | <0.001 | <0.001 |
| ≥60 | 19.5 (17.4 to 21.7) | 14.3 (13.6 to 15.1) | 19.5 (17.4 to 21.9) | <0.001 | <0.001 |
| 15–25 | |||||
| 25–59 | 1.63 (1.48 to 1.79) | 1.41 (1.34 to 1.48) | 1.71 (1.56 to 1.88) | 0.008 | <0.001 |
| ≥60 | 1.47 (1.29 to 1.67) | 1.19 (1.11 to 1.27) | 1.62 (1.42 to 1.85) | 0.004 | <0.001 |
*Small p values indicate that the IRR for the period before the break is significantly higher than that for the period during the break (or the IRR for the period during the break is significantly higher than that for the period after the break).
ILI, influenza-like illness; IRR, incidence rate ratio.