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Background: Antiretroviral pre-exposure prophylaxis reduces sexual transmission of HIV. We assessed whether daily oral use of tenofovir disoproxil fumarate (tenofovir), an antiretroviral, can reduce HIV transmission in injecting drug users., Methods: In this randomised, double-blind, placebo-controlled trial, we enrolled volunteers from 17 drug-treatment clinics in Bangkok, Thailand. Participants were eligible if they were aged 20-60 years, were HIV-negative, and reported injecting drugs during the previous year. We randomly assigned participants (1:1; blocks of four) to either tenofovir or placebo using a computer-generated randomisation sequence. Participants chose either daily directly observed treatment or monthly visits and could switch at monthly visits. Participants received monthly HIV testing and individualised risk-reduction and adherence counselling, blood safety assessments every 3 months, and were offered condoms and methadone treatment. The primary efficacy endpoint was HIV infection, analysed by modified intention-to-treat analysis. This trial is registered with ClinicalTrials.gov, number NCT00119106., Findings: Between June 9, 2005, and July 22, 2010, we enrolled 2413 participants, assigning 1204 to tenofovir and 1209 to placebo. Two participants had HIV at enrolment and 50 became infected during follow-up: 17 in the tenofovir group (an incidence of 0·35 per 100 person-years) and 33 in the placebo group (0·68 per 100 person-years), indicating a 48·9% reduction in HIV incidence (95% CI 9·6-72·2; p=0·01). The occurrence of serious adverse events was much the same between the two groups (p=0·35). Nausea was more common in participants in the tenofovir group than in the placebo group (p=0·002)., Interpretation: In this study, daily oral tenofovir reduced the risk of HIV infection in people who inject drugs. Pre-exposure prophylaxis with tenofovir can now be considered for use as part of an HIV prevention package for people who inject drugs., Funding: US Centers for Disease Control and Prevention and the Bangkok Metropolitan Administration., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: HIV spread rapidly amongst injecting drug users (IDUs) in Bangkok in the late 1980s. In recent years, changes in the drugs injected by IDUs have been observed. We examined data from an HIV vaccine trial conducted amongst IDUs in Bangkok during 1999-2003 to describe drug injection practices, drugs injected, and determine if drug use choices altered the risk of incident HIV infection., Methods: The AIDSVAX B/E HIV vaccine trial was a randomized, double-blind, placebo-controlled trial. At enrolment and every 6 months thereafter, HIV status and risk behaviour were assessed. A proportional hazards model was used to evaluate demographic characteristics, incarceration, drug injection practices, sexual activity, and drugs injected during follow-up as independent predictors of HIV infection., Results: The proportion of participants injecting drugs, sharing needles, and injecting daily declined from baseline to month 36. Amongst participants who injected, the proportion injecting heroin declined (98.6-91.9%), whilst the proportions injecting methamphetamine (16.2-19.6%) and midazolam (9.9-31.9%) increased. HIV incidence was highest amongst participants injecting methamphetamine, 7.1 (95% CI, 5.4-9.2) per 100 person years. Injecting heroin and injecting methamphetamine were independently associated with incident HIV infection., Conclusions: Amongst AIDSVAX B/E vaccine trial participants who injected drugs during follow-up, the proportion injecting heroin declined whilst the proportion injecting methamphetamine, midazolam, or combinations of these drugs increased. Controlling for heroin use and other risk factors, participants injecting methamphetamine were more likely to become HIV-infected than participants not injecting methamphetamine. Additional HIV prevention tools are urgently needed including tools that address methamphetamine use., (Published by Elsevier B.V.)