Peer driven or driven peers? A rapid review of peer involvement of people who use drugs in HIV and harm reduction services in low- and middle-income countries.

Peer involvement in HIV and harm reduction services in low- and middle-income settings is linked to positive health outcomes, shaped by contexts of criminalisation, stigma, and resource scarcity. However, peer involvement is under-theorised, particularly on how contexts shape mechanisms and ultimately outcomes. Efforts to study peer involvement need to develop theory and methods to evaluate the complex mechanisms and contexts that have influence. Finally, there is a need to expand the range of peer roles, to embrace the capacities and expertise of people who use drugs.