[1] Univ Oxford, Clin Res Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
[2] Univ Oxford, Clin Res Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
[3] Yale Univ, Sch Med, Dept Med, New Haven, CT 06510 USA
[4] Univ Hawaii Manoa, Hawaii Ctr AIDS, Honolulu, HI 96822 USA