Table 1.
Unadjusted prevalence risk differences for influenza RNA surface contamination, 2009–2010, Bangkok, Thailand
| Second study (2010) n = 101 households | Both studies (2009, 2010) N = 191 households | |||||||
|---|---|---|---|---|---|---|---|---|
| No. positive*/total | Prevalence risk difference | No. positive*/total | Prevalence risk difference | |||||
| (%) | (%) | (95% CI) | P | (%) | (%) | (95% CI) | P | |
| All | 8/101 (7·9) | 24/191 (12·6) | ||||||
| Study arm | ||||||||
| Control | 6/51 (11·8) | 7·8 | (−2·6,18·1) | 0·1485 | 17/96 (17·7) | 10·3 | (1·1,19·6) | 0·0310 |
| Hand washing | 2/50 (4·0) | 7/95 (7·4) | ||||||
| Gender of index patient | ||||||||
| Female | 5/43 (11·6) | 6·5 | (−4·7,17·6) | 0·2349 | 13/84 (15·5) | 5·2 | (−4·4,14·8) | 0·2820 |
| Male | 3/58 (5·2) | 11/107 (10·3) | ||||||
| Age | ||||||||
| Less than or equal to median | 5/61 (8·2) | 0·7 | (−10·0,11·4) | 0·8991 | 14/96 (14·6) | 4·1 | (−5·3,13·4) | 0·3977 |
| Above median | 3/40 (7·5) | 10/95 (10·5) | ||||||
| Influenza category | ||||||||
| Seasonal (H3N2, H1N1, B) | 3/50 (6·0) | −3·8 | (−14·3,6·7) | 0·4791 | 11/76 (14·5) | 3·2 | (−6·6,13·0) | 0·5178 |
| A(H1N1)2009pdm | 5/51 (9·8) | 13/115 (11·35) | ||||||
| Dew point in household | ||||||||
| Less than or equal to median | 7/48 (14·6) | 12·7 | (2·0,23·3) | 0·0197 | 18/93 (19·4) | 13·2 | (3·8,22·5) | 0·0063 |
| Above median | 1/52 (1·9) | 6/97 (6·2) | ||||||
| Secondary influenza infections in household | ||||||||
| ≥1 case | 4/37 (10·8) | 4·6 | (−7·1,16·2) | 0·4135 | 11/63 (17·5) | 7·3 | (−3·4,18·0) | 0·1522 |
| None | 4/64 (6·3) | 13/128 (10·2) | ||||||
| Reported hand washing of index case (times/day) | ||||||||
| Less than or equal to median | 6/66 (9·1) | 2·8 | (−8·0,13·7) | 0·6300 | 19/113 (16·8) | 9·6 | (0·3,18·8) | 0·0642 |
| Above median | 2/32 (6·3) | 5/69 (7·3) | ||||||
*
Positive for influenza RNA by rRT-PCR from ≥ 1 or 6 surfaces tested on day 3 after onset of symptoms.