Table 2 Secondary attack ratios of qRT-PCR confirmed influenza infection and clinical influenza, intention-to-treat analysis
Confirmation of influenza infection | Control Group | Mask Group | Mask & Hygiene Group | p-value§ | ||||
|---|---|---|---|---|---|---|---|---|
n/n | SAR (95% CI#) | n/n | SAR (95% CI#) | n/n | SAR (95% CI#) | |||
RT-PCR* | All cases | 19/82 | 23 (13-35) | 6/69 | 9 (3-19) | 10/67 | 15 (5-27) | 0.18 |
Influenza A (H1N1) pdm09 | 13/56 | 23 (11-37) | 6/58 | 10 (3-20) | 4/50 | 8 (2-17) | 0.16 | |
Influenza B | 6/26 | 23 (5-48) | 0/11 | 0 | 6/17 | 35 (7-60) | 0.22 | |
Season 2009/2010 | 8/36 | 22 (10-35) | 3/31 | 10 (0-26) | 3/39 | 8 (0-18) | 0.29 | |
Season 2010/2011 | 11/46 | 24 (9-42) | 3/38 | 8 (0-19) | 7/28 | 25 (4-45) | 0.27 | |
Implementation of intervention < 36 h after symptom onset of index patient | 5/22 | 23 (6-39) | 1/14 | 7 (0-23) | 1/24 | 4 (0-16) | 0.17 | |
Clinical (ILI**) | All cases | 14/82 | 17 (7-29) | 6/69 | 9 (3-17) | 6/67 | 9 (3-16) | 0.37 |
Influenza A (H1N1) pdm09 | 10/56 | 18 (7-31) | 6/58 | 10 (3-20) | 3/50 | 6 (0-13) | 0.29 | |
Influenza B | 4/26 | 15 (0-39) | 0/11 | 0 | 3/17 | 18 (0-37) | 0.56 | |
Season 2009/2010 | 6/36 | 17 (6-31) | 4/31 | 13 (3-30) | 3/39 | 8 (0-16) | 0.57 | |
Season 2010/2011 | 8/46 | 17 (2-35) | 2/38 | 5 (0-14) | 3/28 | 11 (0-25) | 0.48 | |
Implementation of intervention < 36 h after symptom onset of index patient | 4/22 | 18 (4-38) | 2/14 | 14 (0-36) | 1/24 | 4 (0-13) | 0.41 | |