Table 3. Association between class or index case characteristics and the process indicators (potential mediators).

	Totaln	Known source of infection of the index casen (%)*	Index case symptomaticn (%)*	Tracing delayMedian (IQR)
Classes (n=1884)
Type of school
Infant-toddler centre	350	157 (44.9)	281 (80.3)	3 (2-5)
Primary school	540	255 (47.2)	355 (65.7)	3 (2-5)
Middle school	496	206 (41.5)	293 (59.1)	3 (2-6)
High school	478	216 (45.2)	360 (75.3)	3 (2-6)
Other educational services	20	7 (35.0)	10 (50.0)	3 (1.5–5)
P value†		0.378	0.001	0.147
Class size
<21	862	375 (41.4)	587 (81.6)	3 (2-5)
≥21	1011	461 (45.6)	707 (69.9)	3 (2-6)
Missing	11	5 (45.5)	5 (45.5)	6 (3-7)
p value†		0.661	0.782	0.367
Index cases (n=1604)
Type of index case
Student	1213	683 (56.3)	957 (78.9)	3 (2-5)
Teacher	391	104 (26.7)	342 (87.5)	3 (2-6)
p value†		<0.001	<0.001	0.486

^*Values are numbers with row percentages.

^†Kruskal-Wallis test.