[1] Guangxi Med Univ, Sect Epidemiol & Stat, Sch Publ Hlth, 22 Shuangyong Rd, Nanning 530021, Guangxi Zhuang, Peoples R China
[2] Guangxi Zhuang Autonomous Reg Ctr Dis Control & P, Sect Acute Communicable Dis Control & Prevent, Nanning, Guangxi Zhuang, Peoples R China