The cost of a late-detected outbreak among people who inject drugs. A modeling study

People who inject drugs (PWID) are at risk for human immunodeficiency virus (HIV) and hepatitis C virus (HCV). In 2009 and 2011, Athens, Greece experienced an HCV and an HIV outbreak among PWID, respectively. Of these, only the 2011 HIV outbreak was detected. However, the public health interventions implemented in response to the HIV outbreak tackled also indirectly the undetected HCV outbreak. The aim of this study is to highlight the potential benefits of an efficient notification system using as a case study the undetected 2009 HCV outbreak among PWID of Athens. More specifically, the study assesses whether an earlier implementation of the same public responses could diminish the scale of the HCV outbreak and estimates the potential cost-savings.

A previous dynamic, stochastic, individual-based model was used to simulate HCV transmission among PWID of Athens, Greece. We calibrated the model to reproduce the observed HCV prevalence. We examined the effect of the non-detection scenario, the 1- or 2-years earlier detection scenarios and compared them to the status quo scenario.

Under the non-detection scenario, 2800 additional PWID would have been infected with HCV compared to the status quo by 2019. On the contrary, if the outbreak was detected 1- or 2- years earlier with immediate interventions, 440 and 970 HCV cases could be averted by 2019, respectively. Non-detection of the outbreak would cost an additional 43.2 (95% Credible interval: 2.7, 59.4) million euros to the healthcare system, compared to the status quo. On the other hand, if there was an efficient notification system to detect the HCV outbreak 1 or 2 years earlier, 6.8-15.6 million euros could have been saved by 2019.

An efficient notification system among PWID is a cost-saving investment that could detect on time and contain future outbreaks, and save valuable resources of the healthcare system.