Since the 1980s, targeted interventions with injecting drug users have largely involved secondary prevention strategies intended to reduce the risk of HIV and make injecting less harmful, rather than primary prevention work that reduces the numbers transitioning to injecting. The problem is how do you reach those who have yet to inject? Paradoxically, one answer may be to target existing injectors.

Getting the point across: a cheap, effective, brief intervention to reduce injecting (PDF)