^*Abbreviation List.

PReventing Injecting by Modifying Existing Responses [PRIMER] Linked Cohort Studies and Inclusion Criteria¹⁸

Cohort Study*	Setting	Inclusion Criteria	Sample size [n]
Vancouver Injection Drug Users Study [VIDUS]	Vancouver	Age 18 or older; HIV negative; injected any drug	n=664
AIDS Care Cohort to Evaluate Access to Survival Services [ACCESS]**	Vancouver	Age 18 or older, HIV positive, past 6-month illicit drug use other than cannabis	n=459
At-Risk Youth Study [ARYS]	Vancouver	Ages between 14 to 26, illicit drug use pre-baseline, homeless or in youth shelter	n=209
Proyecto el Cuete IV [ECIV]	Tijuana	Age 18 or older, drug injection pre-baseline, Spanish or English speaking, lived in Tijuana	n=666

^*PRIMER was approved by research ethics boards at the University of British Columbia (Vancouver), el Colegio de la Frontera Norte (Tijuana), and the University of California San Diego Institutional Review Board (Tijuana and Vancouver).

^**Note: participants in the ACCESS^* study were HIV-positive, resulting in an overrepresentation of people living with HIV from the Vancouver cohort.⁶⁴