Patterns of HCV Transmission May Inform Treatment-As-Prevention Efforts Among People Who Inject Drugs
Hepatitis C (HCV) treatment has been shown to substantially reduce HCV prevalence and transmission among people who inject drugs (PWID). Existing literature, however, has focused on HCV acquisition. To gain a better understanding of HCV transmission among this population, researchers investigated phylogenetic patterns of HCV transmission among 699 young (< 27 years) and older (≥ 27 years) PWID with HCV in Vancouver, Canada and assessed factors associated with pairing (2 participants with phylogenetically-related virus) and clustering (> 3 participants with phylogenetically-related virus) of infections.
- Of the participants, 26% were female, 22% were < 27 years old, 10% seroconverted at some point during the 16 year follow-up period,* 50% were infected with HCV genotype 1a, and 24% had concurrent HIV infection.
- When viral lineage was restricted to clusters believed to have emerged in the previous 5 years, 15% of participants’ HCV infections were phylogenetically related (86 pairs, 21 clusters).
- HCV transmission occurred both within and between younger and older PWID.
- Factors associated with phylogenetic clustering included: younger age, shorter duration since injecting initiation, HIV co-infection, and HCV genotype 3a infection.
Comments:
In this population of PWID, many HCV infections among participants < 27 years old occurred due to transmission events between older and younger PWID, highlighting the fact that treatment-as-prevention strategies will require broad scale-up among both age cohorts. While injecting patterns and networks likely vary based on local factors, these results emphasize how phylogenetic studies can be used to better understand and potentially intervene on the dynamic nature of HCV epidemics among PWID in other settings.
Seonaid Nolan, MD
Reference:
Jacka B, Applegate T, Poon AF, et al. Transmission of hepatitis C virus infection among younger and older people who inject drugs in Vancouver, Canada. J Hepatol. 2016;64(6):1247–1255.