Table 3. Relationship between group influenza status with age and season in growing pigs tested for influenza virus, midwestern United States, June 2009–December 2011*.
| Variable |
Estimate |
Odds ratio (95% CI) |
p value |
|---|---|---|---|
| Intercept |
–1.330 |
NA |
<0.01 |
| Season | |||
| Fall (referent) | NA | NA | NA |
| Spring | 0.741 | 2.0 (1.1– 3.8) | 0.01 |
| Summer | 0.657 | 1.9 (1.0–3.5) | 0.03 |
| Winter | –0.072 | 0.9 (0.4–1.8) | 0.83 |
| Age | –0.041 | 0.9 (0.9–1.0) | 0.09 |
*Repeated measures logistic regression multivariable analysis. Generalized χ2 divided by degrees of freedom = 0.92. NA, not applicable.