Hepatitis C virus clearance, reinfection, and persistence, with insights from studies of injecting drug users: towards a vaccine

Hepatitis C virus (HCV) was discovered more than two decades ago, but progress towards a vaccine has been slow.HCV infection will spontaneously clear in about 25% of people. Studies of spontaneous HCV clearance in chimpanzeesand human beings have identifi ed host and viral factors that could be important in the control of HCV infection andthe design of HCV vaccines. Although data from studies of chimpanzees suggest that protection against reinfectionis possible after spontaneous clearance, HCV is a human disease. Results from studies of reinfection risk afterspontaneous clearance in injecting drug users are confl icting, but some people seem to have protection against HCVpersistence. To guide future vaccine development, we assess data from studies of HCV reinfection after spontaneousclearance, discuss fl aws in the methods of previous human studies, and suggest essential components for futureinvestigations of control of HCV infection