Due to the high cost of improved Hepatitis C virus treatment, in most cases, it is not feasible to offer treatment to all injection drug users at once. In order to optimize the benefits for the overall injection population, targeting HCV treatment appropriately is vital. Previously, treatment has been withheld from active injectors because of the risk that they may become re-infected and limit the benefits to themselves and the whole population.
The authors of this study look at the population-level benefits of treating one chronically HCV infected injection drug user in a population of high- and low- risk users. They then compared the benefits of treating one high or low risk user to develop an optimal treatment strategy.
- High-risk injectors share injecting equipment approximately 7 times more frequently than low-risk injectors.
- When approximately 32% of injectors are infected with Hepatitis C, the preventative impact of treating high and low risk injectors is equivalent
(1 high-risk injector = 1 low-risk injector).
- When Hepatitis C Virus is rare, the benefits of preventing high-risk injectors spreading it to larger numbers outweighs the risk that they will become re-infected.
- When the virus is already very common, fewer injectors can be infected, which reduces the spreading potential of high-risk users. At this point, it is better to focus efforts toward treating lower risk injectors who are less likely to become re-infected.
To enhance the preventative impact of hepatitis C virus treatment, interventions should be targeted based on how often the patient shares injecting equipment. When Hepatitis C virus is relatively uncommon among injectors, it is best to cure infected high-risk injectors. When the virus is relatively common, low-risk injectors should be targeted.
De Vos, A.S., Prins, M., and Kretzschmar, M.E.E. (2015). Hepatitis C virus treatment as prevention among injecting drug users: who should we cure first? Addiction. Vol.110, pp. 975-983.