The causes of vaccine failure were discuss ed,which includes the persistence of maternal antibodies,quality of vaccine,the immunosuppressive effect of parvovirus and variation of CDV.

• 分析免疫失败的原因,主要是母源抗体干扰、疫苗质量差、其它病毒的免疫抑制以及CDV流行株可能发生了变异等因素的影响。