Injecting drug use among gay and bisexual men in New Zealand: Findings from national human immunodeficiency virus epidemiological and behavioural surveillance

Introduction and Aims Gay and bisexual men (GBM) who inject drugs are disproportionately affected by human immunodeficiency virus (HIV) because of dual transmission risks. New Zealand has a progressive history of harm reduction and was the first country to publicly fund needle exchange programs in 1988 for people who inject drugs (PWID). We combine national HIV epidemiological and bio-behavioural surveillance data to understand HIV risk among this subpopulation. Design and Methods We examine trends in new HIV diagnoses 1996-2018 by mode of transmission, and compare HIV cases attributed to sex between men (MSM-only), MSM/injecting drug use (IDU) and IDU-only. IDU among GBM in a national HIV behavioural surveillance survey was also examined. We compare GBM by IDU status (never, 'recent', previous) and identified predictors of recent IDU. Results Of 1653 locally-acquired HIV diagnoses 1996-2018, 77.4% were MSM-only, 1.5% MSM/IDU, 1.4% IDU-only and 14.2% heterosexual mode of transmission. On average, just one HIV diagnosis attributed to MSM/IDU and IDU, respectively, occurred per annum. MSM/IDU cases were more likely than MSM-only cases to be indigenous Maori ethnicity. Of 3163 GBM survey participants, 5.4% reported lifetime IDU and 1.2% were recent IDU. Among GBM, HIV positivity was 20% among recent IDU and 5.3% among never injectors. Predictors of recent IDU were: age under 30; more than 20 male partners; female partner; condomless intercourse; HIV positivity. Discussion and Conclusion New Zealand has averted high endemic HIV rates seen among GBM and PWID in other countries and results have been sustained over 30 years.