become victims of rape.24 The risk of transmission of HIV is highest in violent sexual activities. For several years, most western European countries have provided condoms in prison and there is now clear evidence that condoms, lubricants and dental dams are used in sexual activities by prisoners if they are easily and anonymously accessible, that provision of condoms has not induced an increase of sexual activity in prison and that, because there is no evidence of negative unintended side‑efects, condom provision is accepted by most prisoners and staf once it is introduced.25 However, condom provision without efective policies to counter sexual vio‑ lence is clearly insufcient to prevent sexual transmission in prison. Policies to prevent sexual violence must include avoidance of overcrowding, adequate stafng and surveillance, non‑tolerance of informal hierarchies among prisoners and structural improvements enabling staf to protect vulnerable prisoners from sexual violence. In reports on several country visits, the CPT has expressed concern about the lack of condom provision26 and defcient protection of prisoners from sexual violence.27 3.6 Medical preventive interventions Vaccination In line with the policy brief of the United Nations Ofce on Drugs and Crime (UNODC) on HIV prevention and care in prisons and other closed settings,28 free provision to prisoners and prison staf of hepatitis B vaccination is rec‑ ommended. It is reasonable to ofer hepatitis A vaccination to patients with chronic hepatitis B or C, since additional infection with hepatitis A virus can cause acute fatal liver failure. 24. Jürgens R., Nowak M. and Day M: “HIV and incarceration: prisons and detention”. Journal of the International AIDS Society 14:26 (2011) . 25. WHO/UNODC/UNAIDS: Interventions to address HIV in prisons: comprehensive review, Evidence for Action Technical Paper (Geneva 2007); WHO/UNODC/UNAIDS: Efectiveness of interventions to address HIV in prisons, Evidence for Action Technical Paper (Geneva, 2007). 26. CPT/Inf (2005)1; (2007)40; (2011)20. 27. CPT/Inf (2007)32; (2009)8; (2011)22; (2011)24; (2012)9. 28. UNODC: HIV prevention and care in prisons and other closed settings: a comprehensive package of interventions, Policy Brief (Vienna 2012). Prison health care and medical ethics Page 60