Table 2.

Per-Contact Infectivity (%) and 95% CI of HCV Acquisition Associated With Receptive Needle Sharing

Group	No.	Infectivity, %	95% CI, %
All participants pooled, including those who remained HCV negative	344	0.25	0.10–0.43
Participants with only primary HCV infection	101	0.89	0.20–2.27
Participants with reinfection (following clearance)	17	1.62	0.44–8.14
Participants with any HCV infection (primary or reinfection)	118	1.12	0.48–2.36

Infectivity is from maximum likelihood estimate; confidence interval is estimated using the nonparametric bootstrap.

Abbreviations: CI, confidence interval; HCV, hepatitis C virus.