title: HIV-prevention science at a crossroads: advances in reducing sexual risk.
abstract: OBJECTIVE
  We review the current state of evidence-based prevention strategies for reducing sexual transmission of HIV. The combined programmatic and scientific efforts through 2008 to reduce sexual transmission of HIV have failed to reduce substantially the global pandemic.
  
  
  RESULTS
  Prevention interventions to reduce HIV infection target behavioral, biomedical, and structural risk factors. Some of these prevention strategies have been evaluated in randomized clinical trials (RCTs) with HIV seroincidence endpoints. When RCTs are not feasible, a variety of observational and quasiexperimental research approaches can provide insight as to program effectiveness of specific strategies. Only five RCTs have demonstrated a notable decrease in sexually acquired HIV incidence. These include the Mwanza study of syndromic management of sexually transmitted diseases and three male circumcision trials in East Africa; a microbicide trial reported in 2009 shows substantial promise for the efficacy of PRO 2000 (0.5% gel).
  
  
  CONCLUSIONS
  The combined programmatic and scientific efforts to reduce sexual transmission of HIV have made incremental progress. New prevention tools are needed to stem the continued spread of HIV, though microbicides and vaccines will take many more years to develop, test, and deploy. Combination strategies of existing modalities should be tested to evaluate the potential for more proximate prevention benefits.
authors.affiliation: Institute for Global Health and Department of Pediatrics at Vanderbilt University School of Medicine, 2215 Garland Drive (319 Light Hall), Nashville, TN 37232-0242, USA. sten.vermund@vanderbilt.edu
authors.forename: Sten H
authors.initials: SH
authors.lastname: Vermund
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Allen
authors.forename: Quarraisha Abdool
authors.initials: QA
authors.lastname: Karim
mesh_terms: D000349:Africa / Q000453:epidemiology; D002986:Clinical Trials as Topic; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission*; D006801:Humans; D008297:Male; D012308:Risk Management / Q000379:methods*; D040242:Risk Reduction Behavior