Evidence from the drugs field

Peer work in the drugs field has been shown to be effective as a method of HIV risk reduction among drug user communities in the Netherlands, the US, the UK and Australia. (source: Dowsett
http://www.health.gov.au/internet/main/publishing.nsf/Content/46CCB33C239077AFCA2570A7000D8AEC/$File/hepc-idu.pdf).

It has become internationally accepted that outreach work including peer workers is extremely effective in reaching ‘hard to reach’ communities and in providing information to support behavioural changes.
UNAIDS http://data.unaids.org/publications/IRC-pub01/jc291-peereduc_en.pdf
WHO, http://whqlibdoc.who.int/publications/2004/9241591528.pdf

Data from research in the US, Ukraine and China show that outreach that included peers (peer-driven interventions) ‘were more effective in contacting a wider range of hidden groups and supporting them in less risky behaviour than outreach without peers’ (see, for instance, a study on individual and network interventions with injecting drug users in 5 Ukraine cities, Latkin et al., 2011 http://www.experts.scival.com/jhu/pubDetail.asp?t=pm&;id=20395584&n=Carl+Latkin&u_id=582)