Table 1. Baseline sociodemographic characteristics and risk behaviors among young IDU in HCV vaccine trial willingness survey (n=67) and participants in HCV negative cohort study (n=202), San Francisco, 2003-2008.

	Vaccine trial survey participants % (95% CI) or median (IQR)	HCV negative UFO cohort participants % (95% CI) or median (IQR)	p-value
Age	23.7 (21.1 – 27.2)	22.8 (20.6 – 25.5)	n.s.*
Male	65.7	68.8	n.s.
Non-white race/ethnicity	20.0	30.2	n.s.
Less than high school education	36.9	45.6	n.s.
Homeless last 3 mo.	67.2	67.0	n.s.
Years injecting	5.1 (2.9 – 9.2)	4.1 (1.7 – 7.6)	n.s.
No. of daily injections	3.0 (1.8 – 4.0)	2.0 (1.0 – 3.0)	n.s.
Drug used most days last month - heroin	69.4	59.1	n.s.
Borrowed used needle last 3 mo.	34.9	36.2	n.s.
Incarcerated last 3 mo.	23.4	30.8	n.s.

^*non-signficant, p≥0.05