1. Total population
- In 2016, 3.5 million people were chronically infected with HCV
2. Current PWID
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
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