Factor

Category

Cases n = 31 (%)

Control n = 62 (%)

OR (95% CI)

p-value

Friend contact

Yes

No

20 (64.5)

11 (35.5)

15 (24.2)

47 (75.8)

5.6 (2.2 - 14.5)

<0.01

Classmate contact

Yes

No

18 (58.1)

13 (41.9)

14 (22.6)

48 (77.2)

4.7 (1.8 - 12.0)

<0.01

Roommate contact

Yes

No

21 (67.7)

10 (32.3)

21 (33.9)

41 (66.1)

4.1 (1.6 - 10.3)

<0.01

Sharing clothes

Yes

No

11 (35.5)

20 (64.5)

9 (14.5)

53 (85.5)

3.2 (1.2 - 9.0)

0.015

Dormitory size

Yes

No

23 (74)

8 (26)

33 (53.0)

29 (47.0)

2.5 (1.0 - 6.5)

0.05

History of varicella like rash

Yes

No

5 (16.1)

26 (83.9)

40 (64.5)

22 (35.5)

0.1(0.04 - 0.31)

<0.01