Liu Huimeng1,Li Rui1, Wang Yutong1,Ji Zhenhao2,Mi Baibing1,Chen Fangyao1,Shen Mingwang1,Qi Xin1,Pei Leilei1,Zeng Lingxia1,Hou Tiejun2,Zhuang Guihua1
1 School of Public Health, Xi′an Jiaotong University Health Science Center, Xi′an 710061, China; 2 Xi′an Center for Disease Control and Prevention, Xi′an 710000, China