Table 2.

Logistic regression results for the different influenza A strains

Variables	β	SE	OR	95% CI		p-value
				Lower	Upper
H3N2/415 (AIC: 338.07)
(Intercept)	−4.315	0.387	0.013	0.006	0.027	0.000	***
Familial farm
Company farm	1.269	0.573	3.558	1.195	11.331	0.027	*
Unknown farm	1.134	0.645	3.107	0.842	10.698	0.079
Hung Yen
Hanoi	0.964	0.608	2.621	0.817	8.837	0.113
Other	0.074	0.599	1.077	0.317	3.394	0.902
Unknown	−0.378	0.693	0.685	0.178	2.740	0.585
No concurrent isolation
Concurrent isolation	0.690	0.325	1.993	1.046	3.773	0.034	*
H3N2/601 (AIC: 1078.8)
(Intercept)	−0.465	0.110	0.628	0.505	0.779	0.000	***
Hung Yen
Hanoi	−1.918	0.307	0.147	0.077	0.259	0.000	***
Other	−0.191	0.198	0.826	0.558	1.212	0.334
Unknown	−0.456	0.197	0.634	0.428	0.928	0.021	*
Before 1st isolation
After 1st isolation	−0.632	0.170	0.532	0.379	0.738	0.000	***
H1N2/826 (AIC: 946.59)
(Intercept)	−1.920	0.173	0.147	0.103	0.204	0.000	***
Familial farm
Company farm	−0.543	0.285	0.581	0.329	1.009	0.057
Unknown farm	−0.121	0.307	0.886	0.478	1.598	0.694
Hung Yen
Hanoi	−0.224	0.353	0.799	0.393	1.578	0.526
Other	0.332	0.229	1.394	0.886	2.178	0.147
Unknown	0.572	0.327	1.771	0.937	3.392	0.081
Before 1st isolation
After 1st isolation	0.914	0.180	2.493	1.759	3.572	0.000	***
H1N1/pdm (AIC: 1179.9)
(Intercept)	−0.636	0.112	0.530	0.425	0.658	0.000	***
Familial farm
Company farm	−0.601	0.168	0.549	0.393	0.759	0.000	***
Unknown farm	−0.846	0.206	0.429	0.284	0.637	0.000	***
No concurrent isolation
Concurrent isolation	0.278	0.142	1.321	0.999	1.744	0.050
H1N1/EA (AIC: 276.55)
(Intercept)	−6.275	0.769	0.002	0.000	0.007	0.000	***
Hung Yen
Hanoi	1.221	0.474	3.391	1.310	8.593	0.010	**
Other	1.173	0.437	3.232	1.366	7.726	0.007	**
Unknown	0.549	0.525	1.731	0.579	4.712	0.296
Not positive to other H1
Positive to other H1	3.245	0.733	25.650	7.713	159.067	0.000	***

Only sera from slaughterhouses were included *p-value ≤0.05; **p-value ≤0.01; ***p-value ≤0.001