Subclinical Highly Pathogenic Avian Influenza Virus Infection among Vaccinated Chickens, China oleh Qing-Xia Ma, Wen-Ming Jiang, Shuo Liu, Su-Chun Wang, Qing-Ye Zhuang, Guang-Yu Hou, Xiang-Ming Liu, Zheng-Hong Sui, Ji-Ming Chen