"The joint UNODC/WHO/UNAIDS/World Bank estimate of the number of PWID worldwide in 2018 is 11.3 million (range: 8.9 million to 15.3 million), corresponding to 0.23 per cent (range: 0.18 to 0.31 per cent) of the population aged 15–64. This estimate is based on the most recent information available and assessment of the methodologies of the different sources.108
"There is no change between the 2017 and 2018 estimates of PWID; however, any trend data must be viewed with caution, as methodologies may have changed. The 2018 global estimate of PWID is based on 122 countries, representing almost 90 per cent of the global population aged 15–64, compared with 110 countries in 2017. Of all the available sources in 2018, the estimates for at least 74 countries (61 per cent) were based on a “class A methodology” such as indirect prevalence estimation methods (e.g., the capture-recapture method, network scale-up method and multiplier method).109
"Owing to the criminalization of drug use, punitive laws, stigma and discrimination against people who use or inject drugs in many parts of the world, conventional survey methods have been found to underestimate the actual population size because of the hidden nature of PWID;110, 111, 112 therefore, only indirect methods have been shown to reflect the situation of PWID with greater accuracy. Overall, new or updated estimates of PWID were available for 40 countries in 2018.
"Although the exact extent of injecting drug use is not known, estimates are more precise in some regions than others as a result of better data coverage and/or methodologies and the use of more recent data. Data on PWID vary between the regions in terms of coverage of the total population aged 15–64, with Asia having the highest coverage, at 95 per cent, and Africa having the lowest, at 68 per cent. At the subregional level, North America, South-West Asia, South Asia, Eastern Europe and South-Eastern Europe are fully covered, whereas data on PWID in the Caribbean only covers just over one third of the total population; therefore, data from that subregion must be interpreted with caution. Compared with 2017, coverage of the population in Africa increased substantially overall, from 58 to 68 per cent in 2018.
"The prevalence of PWID aged 15–64 in 2018 continues to be the highest in Eastern Europe (1.26 per cent) and Central Asia and Transcaucasia (0.63 per
cent). Those percentages are, respectively, 5.5 and 2.8 times higher than the global average. More than a quarter of all PWID reside in East and South-East
Asia, although the prevalence itself is relatively low (0.19 per cent). The three subregions with the largest numbers of PWID (East and South-East Asia, North America and Eastern Europe) together account for over half (58 per cent) of the global number of PWID. It is noteworthy that, as in previous years, while three countries – China, the Russian Federation and the United States – account for just 27 per cent of the global population aged 15–64, they are home to almost half (43 per cent) of all PWID."
World Drug Report 2020. Booklet Two: Drug Use and Health Consequences. June 2020. United Nations publication, Sales No. E.20.XI.6).