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

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)