[1] Yale Univ, Dept Social & Behav Sci, Yale Sch Publ Hlth, New Haven, CT 06520 USA
[2] Columbia Univ, Mailman Sch Publ Hlth, Dept Sociomed Sci, New York, NY USA
[3] Univ Tromso, Dept Community Med, Tromso, Norway
[4] Stop Sida, Ctr Estudis Epidemiol Infecc Transmissio Sexual &, Barcelona, Spain
[5] Verona Univ Hosp, Infect Dis Sect, Dept Pathol, Verona, Italy
[6] Robert Koch Inst, Dept Infect Dis Epidemiol, Berlin, Germany
[7] London Sch Hyg & Trop Med, Dept Social & Environm Hlth Res, Sigma Res, London, England
[8] Swiss Fed Off Publ Hlth, Infect Dis Div, Bern, Switzerland