A case study investigating the effects of emergency vaccination with Brucella abortus A19 vaccine on a dairy farm undergoing an abortion outbreak in China

Table 2 Multivariable logistic regression analysis of risk factors associated with brucellosis seropositivity

Risk factors	Category levels	Estimate	Standard error	Odds ratio, 95% CI	p value ^‡
Constant		-3.30	0.97		< 0.001
Presence of abortion	Yes	3.06	0.90	21.36 (4.37, 168.42)	< 0.001
	No			1.00 (reference)
Shed code	A2	2.32	1.12	10.22 (1.39, 128.02)	0.037
	B1			1.00 (reference)
	B2	0.95	1.14	2.59 (0.29, 31.69)	0.405
	C1	2.83	1.04	16.99 (2.81, 190.26)	0.006