1. Total population
  • In 2016, 3.5 million people were chronically infected with HCV
2. Current PWID
  • (38.1% to 68%) of current PWID are infected with HCV in 2016
3. Scaling to a population (assuming a growing PWID population)
  • In 2007 there were 2,248,500 PWID (current)

  • Allow PWID (current) population to grow with two model fitting parameters
4. Fit multiplier parameter for force of infection to model increasing incidence of HCV
  • Flat prior to 2009
  • 3 to 4 fold increase in incidence between 2010 and 2018

  • Assume increasing incidence and flattening in 2030 and steady incidence until 2040
5. Fit epidemic model parameters for best fit to 2 to 4. Allow the following model parameters to vary
  • Calibration multiplier for force of infection

  • Relapse (former to current) rate and Injecting career length (current to former)
6. Assume split of HCV cases as 50%, 35% and 15% in PWID (current and former), general population and prisoners, respectively
  • Adjust the split such that current PWID account for (74% to 82%) of incident cases
7. Number of former PWID
  • Former PWID population with HCV = 50%* 3.5million - fitted pop in 2016 (point 3) * fitted prevalence in point 2
8. Endemic trend for general population
  • Chronic HCV is assumed to be endemic in the general population and in steady state, i.e. constant