[1] Univ Hong Kong, LKS Fac Med, Dept Family Med & Primary Care, Hong Kong, Peoples R China
[2] Univ Hong Kong, Shenzhen Hosp, Dept Gen Practice, Shenzhen, Peoples R China
[3] Univ Hong Kong, LKS Fac Med, Sch Nursing, Hong Kong, Peoples R China
[4] Univ N Carolina, Sch Med, Dept Med, Div Infect Dis, Chapel Hill, NC 27515 USA
[5] London Sch Hyg & Trop Med, Fac Infect & Trop Dis, London, England
[6] Alfred Hlth, Melbourne Sexual Hlth Ctr, Melbourne, Vic, Australia
[7] Monash Univ, Cent Clin Sch, Melbourne, Vic, Australia
[8] UCL, Ctr Clin Res Infect & Sexual Hlth, Inst Global Hlth, London, England