Table 2. The number of depopulated birds, the number of depopulated units and direct costs of the two different strategies in China from 2004 to 2012.

Strategy	Variable
Destruction without vaccination	Total number of birds in depopulated flocks (thousands)	19,301.36
	Total number of depopulated flocks (thousands)	185.66
	Control cost (billion yuan)	0.63
	Direct cost (billion yuan)	0.63
Vaccination plus destruction	Total number of birds in depopulated flocks (thousands)	1,799.89
	Total number of depopulated flocks (thousands)	16.68
	Control cost (billion yuan)	0.05
	Vaccination cost (billion yuan)	46.35
	Direct cost (billion yuan)	46.4