Effects of school breaks on influenza-like illness incidence in a temperate Chinese region: an ecological study from 2008 to 2015

Chu, Yanhui; Wu, Zhenyu; Ji, Jiayi; Sun, Jingyi; Sun, Xiaoyu; Qin, Guoyou; Qin, Jingning; Xiao, Zheng; Ren, Jian; Qin, Di; Zheng, Xueying; Wang, Xi-Ling

R 2 values for the five age groups (0-4, 5-14, 15-24, 25-59 and 60 years or older) ranging from 0.44 to 0.56. After incorporating the autocorrelation within error terms, we estimated IRRs of during/after to before winter break and their CIs (table 2) . During-to-before IRRs were smaller than 1 for all age groups. However, the starting time and duration of the ILI reduction varied across different age groups. In age group of 15-24, ILI incidence dropped substantially by around 40% during the whole school break and lasted for 4 weeks thereafter. Declines of during-to-before IRRs for age groups of 0-4 and 5-14 were also observable but not necessarily smaller than declines in adults (table 2). For adults (age 25-59 and 60 years or older), ILI reductions were statistically significant in the second and third week of the break and lasted for about 2 weeks (table 2). Among all age groups, incidence of ILI visits returned to regular patterns with none of after-before IRRs statistically significant 3 weeks after the end of winter breaks (table 2) .