Table 1.

Parameter table including uncertainty intervals. TEDs denotes the drug treatment episode dataset.

Parameter	Symbol	Units	Values (sampled range)	Reference
PWID and HCV-related parameters
PWID HCV chronic prevalence in 2015		–	45 – 65%, uniform distribution	Contact tracing data33
Average infection rate	$R{\pi }_1$	per year	Varied to fit sampled HCV prevalence in 2015, and increased by factor after 2010 to achieve 4–7 fold increase in incident infections	Acute HCV surveillance data34,35
Average proportion of infections that spontaneously clear	$\delta$	–	0.22 – 0.29, uniform distribution	32
PWID recruitment rate	$\theta$	per year	Varied to fit total population of 436–600 PWID in 2015, and increased by factor after 2008 to fit 2–3 fold increase in PWID population between 2008–2013	Contact tracing data33 and TEDs data36
Increase in PWID population size between 2008 and 2013	p		2 – 3, uniform distribution	TEDs data36
Average duration of injecting until cessation	$\frac{1}{{\mu }_1}$	years	5 – 20, uniform distribution	Unpublished Scott county SSP data and other data23,37–39
Average drug-related mortality rate	${\mu }_2$	per year	0.57% (0.41–0.73%), Poisson distribution	USA sites from40
Average non drug-related mortality rate	${\mu }_3$	per year	0.14%, Poisson distribution	41 for 35–39 year olds in US
Treatment parameters
SVR rate	$\alpha$	–	85 – 95%, uniform distribution	43
Duration of treatment	$\omega$	weeks	12
Treatment number	${\mathrm{\Phi }}_1$	number per year	Varied to reduce HCV prevalence or incidence by 90% by 2020/25/30.
Harm reduction intervention parameters
Relative risk of acquiring HCV while:
On MAT	$\mathrm{\Gamma }$	–	0.50 (0.40–0.63), log normal distribution	Cochrane Systematic review13
On SSP	$\mathrm{\Pi }$	–	0.44 (0.24–0.80), log normal distribution
On both MAT and SSP	$\mathrm{{\rm B}}$	–	0.29 (0.13–0.65), log normal distribution
Duration on MAT/SSP	1/ $\gamma$	years	0.99 (0.64–1.50), normal distribution	42
Recruitment rate MAT	$\beta$	per year	Varied to give 25% or 50% coverage by mid-2017
Recruitment rate SSP	$\eta$	per year	Varied to give 50% coverage by mid-2016