Government of the People's Republic of China - Institute for Immunization and Prevention, Government of the People's Republic of China - Institute for Immunization and Prevention, Government of the People's Republic of China - Institute for Immunization and Prevention, Government of the People's Republic of China - Institute for Immunization and Prevention, Government of the People's Republic of China - Institute for Immunization and Prevention, Government of the People's Republic of China - Institute for Immunization and Prevention, Government of the People's Republic of China - Institute for Immunization and Prevention, Government of the People's Republic of China - Institute for Immunization and Prevention, Peking University, School of Public Health, Department of Laboratorial Science and Technology, Peking University, School of Public Health, Department of Laboratorial Science and Technology, Dongcheng Center for Disease Control and Prevention - Institute for Infectious Diseases and Endemic Diseases Prevention and Control, FengTai Center for Disease Control and Prevention - Institute for Infectious Diseases and Endemic Diseases Prevention and Control, Haidian Center for Disease Control and Prevention - Institute for Infectious Diseases and Endemic Diseases Prevention and Control, Tsinghua University, Shunyi District Centers for Disease Control and Prevention - Institute for Infectious Diseases and Endemic Diseases Prevention and Control, Shijingshan Center for Disease Control and Prevention - Institute for Infectious Diseases and Endemic Diseases Prevention and Control, Peking University, School of Public Health, Department of Laboratorial Science and Technology and Government of the People's Republic of China - Institute for Immunization and Prevention