HCV prevalence can predict HIV epidemic potential among people who inject drugs: mathematical modeling analysis

BMC Public Health

Table 1 Description of the dynamical regimes of the overlapping epidemiology of HCV and HIV infections among people who inject drugs

	HCV prevalence		HIV prevalence		RR _HCV/HIV ^ab	OR _HCV/HIV ^ab
	Range	Description	Range	Description	Range	Range
Regime I	<1%	Below sustainability	<1%	Below sustainability	..	..
Regime II	1–28%	Above sustainability - low scale HCV epidemic	<1%	Below sustainability	..	..
Regime III	28–45%	Large scale HCV epidemic	1–5%	Above sustainability threshold for HIV epidemic expansion and below concentration threshold	3.7-3.5	4.1-4.0
Regime IV	45–70%	Large scale HCV epidemic	5–24%	Concentrated HIV epidemic	3.5-1.8	4.0-2.3
Regime V	70–80%	Very large scale HCV epidemic	24–42%	Large scale HIV epidemic	1.8-1.2	2.3-1.5
Regime VI	>80%	Approaching maximum prevalence	>42%	Very large scale HIV epidemic and approaching maximum prevalence	<1.2	<1.5

^a We are reporting the range of RR and OR excluding those corresponding to the immediate vicinity of the HCV threshold for HIV sustainable transmission
^b The RR_HCV/HIV and OR_HCV/HIV are reported in descending order to reflect the decreasing trend in the ratios as a function of injecting risk behavior as per Fig. 7

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