[1] Chinese Ctr Dis Control & Prevent, Natl Inst Viral Dis Control & Prevent, NHC Key Lab Biosafety, Beijing 100101, Peoples R China
[2] Ctr Dis Control & Prevent Zhejiang Prov, Hangzhou 310051, Peoples R China
[3] Chinese Ctr Dis Control & Prevent, Chinese Field Epidemiol Training Program, Beijing 100101, Peoples R China
[4] Chinese Ctr Dis Control & Prevent, Key Lab Surveillance & Early Warning Infect Dis, Div Infect Dis, Beijing 100101, Peoples R China