1 China-Australia Joint Research Center for Infectious Diseases, School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, China; Key Laboratory for Disease Prevention and Control and Health Promotion of Shaanxi Province, Xi'an, China.
2 China-Australia Joint Research Center for Infectious Diseases, School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, China.
3 China-Australia Joint Research Center for Infectious Diseases, School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, China; Melbourne Sexual Health Centre, Alfred Health, Melbourne VIC, Australia; Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne VIC, Australia. Electronic address: lei.zhang1@xjtu.edu.cn.