Table 2. Multivariate analysis of independent factors associated with influenza A(H1N1)pdm09 infection among students <18 years of age, Beijing, China*.
| Variable | p value | Matched OR (95% CI) |
|---|---|---|
| Vaccination against influenza A(H1N1)pdm09 | ||
| No | Referent | |
| Yes |
<0.001 |
0.07 (0.04–0.11) |
| Handwashing immediately after sneezing | ||
| No | Referent | |
| Yes |
<0.001 |
0.49 (0.33–0.72) |
| Sleep time, h/day | ||
| <7 | Referent | |
|
>7 |
0.042 |
0.62 (0.38–0.98) |
| Classroom space/student, m2 | ||
| <1.6 | Referent | |
| ≥1.6 |
<0.001 |
0.11 (0.04–0.31) |
| Participation in outdoor activities after class | ||
| No | Referent | |
| Yes |
0.029 |
0.60 (0.38–0.95) |
| Frequency of classroom ventilation | ||
| >1×/h | Referent | |
| 1×/h |
0.023 |
0.60 (0.39–0.93) |
| Mode of transportation to and from school | ||
| Closed (taxi, public transportation, school bus, car) | Referent | |
| Open (walking,
bicycle, motorcycle) |
0.010 |
0.58 (0.39–0.88) |
| Participation in clustered social activities after school | ||
| No | Referent | |
| Yes | 0.025 | 2.08 (1.10–3.95) |
*Ten variables were included in multivariate conditional logistic regression analysis. Backward conditional logistic regression was conducted by removing variables with p>0.10, and 8 variables remained in the final regression model. All statistical tests were 2-sided, and significance was defined as p<0.05. The statistic for each variable was obtained after adjustment for other 7 variables in the final regression model.