. 2017 Sep 8;12(9):e0184527. doi: 10.1371/journal.pone.0184527

Table 2. Median days of ILI sickness and ILI incidence rate in four schools.

Surveillance school	Type of school	Total number of students			Median daily number with ILI (range)			ILI incidence rate (%)
Surveillance school	Type of school	2012	2013	2014	2012.9–12	2013	2014	2012.9–12^*	2013	2014
A	Primary	1438	1516	1534	2(0,10)	1(1,5)	2(0,12)^a	8.97	6.93	12.13
B	Primary	1713	1683	1798	1(0,7)	1(1,5)	2(0,40)^a	1.81	6.24	16.35
D	Primary	1247	1397	1356	1(0,5)	0(0,8)	3(1,42)^a	2.57	3.22	20.28
C	Middle	1454	1644	1485	0(0,5)	1(0,5)	1(0,16)^a	1.24	4.56	9.16
Total		5852	6258	6139				3.59^§	5.27^§	14.51^§

ILI: Influenza-like illness

*Quarterly incidence rate

^§ILI Incidence rate in 2014 was higher than that in 2013 and September to December 2012. (χ² = 298.02, p = 0.00001; χ² =, p = 0.00001)

^a The high absence occurred during an influenza outbreak.