A proportion of HCV infected individuals do not fall into any currently recognized risk group. It is thought that some of these cases may have had exposure to injected drugs many years ago which they have forgotten or are unwilling to discuss. It is also possible that many persons were infected in the early 50s during mass vaccination programs in schools and camps. As well, programs for the poor often used cost cutting measures which included the recycling of medical devices (syringes, needles) which should have been thrown away. Furthermore, blood products have been used in the making of many vaccines and in the 50s and 60s these products were not screened for HCV.
