Improving the data to strengthen the global response to HIV among people who inject drugs.

Recent systematic reviews have provided a global picture of injecting drug use, HIV and the global response to HIV epidemics among people who inject drugs. They have also revealed significant gaps in our knowledge, in both the problem and the response. It is clear that the prevalence of injecting drug use, and of HIV among injecting populations, varies geographically, differing hugely both within and across countries. In many cases, however, data on the number of drug injectors, and of the proportion who are living with HIV, is often unavailable or inaccurate, and gaps exist in many low income countries. The response to injecting drug use and HIV also varies hugely; both the nature and the scale of the response show marked geographic variation. The lack of quality data acts as an impediment to accurate assessments of effective and targeted responses to HIV among people who inject drugs. It is encouraging that the comprehensive suite of interventions considered "essential" by UN agencies in the response to HIV among people that inject drugs is being introduced in more countries now than ever before. Nonetheless, there remains an urgent need for more and higher quality data to be collected, in order to sufficiently inform, improve and ultimately evaluate the response.