Table 1 Baseline characteristics of index patients and household contacts, stratified by season and intervention group

Index Cases - n

13

11

17

17

15

11

Influenza virus subtype:

   A(H1N1)pdm09 - n/n (%)

13/13 (100)

11/11(100)

17/17 (100)

8/17 (47)

11/15 (73)

5/11 (45)

   B - n/n (%)

0

0

0

10/17 (53)

4/15 (27)

6/11 (55)

Age (years) - median (IQR)

8 (7-10)

7 (5-10)

7 (4-10)

8 (6-11)

8 (4-9)

7 (5-9)

Age < 14 years - n/n (%)

12/13 (92)

11/11(100)

16/17 (94)

17/17 (100)

14/15 (93)

11/11 (100)

Sex male - n/n (%)

5/13 (39)

5/11 (45)

10/17 (59)

13/17 (77)

10/15 (67)

7/11 (64)

Vaccinated* - n/n (%)

0

0

0

2/17 (12)

2/15 (13)

0

Antiviral Therapy** - n/n (%)

3/13 (23)

0

2/17 (12)

11/17 (65)

11/15 (73)

10/11 (91)

Chronic Illness - n/n (%)

1/12 (8)

1/11 (9)

0

4/17 (24)

2/15 (13)

0

Symptoms:

   Fever/Chills - n/n (%)

13/13(100)

11/11(100)

17/17(100)

17/17(100)

15/15(100)

11/11(100)

   Cough - n/n (%)

12/13 (92)

11/11(100)

16/17 (94)

16/17 (94)

14/15 (93)

10/11 (91)

   Sore Throat - n/n (%)

4/13 (31)

6/11 (55)

9/17 (53)

10/17 (59)

9/15 (60)

7/11 (64)

   Myalgia - n/n (%)

11/13 (85)

9/11 (82)

11/17 (65)

14/17 (82)

14/15 (93)

9/11 (82)

Symptom onset to rando-misation (hours) - mean ± SD

23.1 (3.7)

27.5 (12.4)

27.5 (11.5)

28.1 (13.9)

35.7 (8.7)

33.2 (11.2)

Symptom onset to first household visit - mean ± SD:

   < 36 h

6/13 (46)

5/11 (46)

9/17 (52)

4/17 (24)

1/15 (7)

1/11 (9)

   36-48 h

4/13 (31)

2/11 (18)

4/17 (24)

9/17 (52)

7/15 (47)

6/55 (55)

   48-60 h

3/13 (23)

4/11 (36)

4/17 (24)

0

2/15 (13)

1/11 (9)

   > 60 h

0

0

0

4/17 (24)

5/15 (33)

3/11 (27)

Household size - mean ± SD

3.8 (1.2)

3.8 (1.2)

2.2 (1.1)

3.9 (1.3)

3.5 (0.9)

3.7 (1.1)

Household Contacts - n

36

31

39

46

38

28

Age (years) - median (IQR)

35 (18-40)

37 (12-43)

34 (19-42)

38 (12-43)

35(17-42)

35 (15-43)

Age < 14 years - n/n (%)

6/36 (17)

8/31 (26)

6/39 (15)

13/46 (28)

8/38 (21)

6/28 (21)

Sex male - n/n (%)

18/36 (50)

15/31 (49)

17/39 (44)

21/46 (46)

19/38 (50)

16/28 (57)

Vaccinated* - n/n (%)

0

1/31 (3)

1/39 (3)

6/46 (13)

7/38 (18)

1/28 (4)

Chronic Illness - n/n (%)

3/35 (9)

2/27 (7)

3/37 (8)

13/46 (28)

8/38 (21)

3/28 (11)