Why are IDUs more vulnerable?

The sharing of injection implements by drug users is a major infection route for HIV. The term 'injection implements' includes syringes, needles and spoons. Such things may be shared for a number of different reasons; sometimes it is difficult to get hold of syringes and needles and sometimes the sharing may be a kind of ritual, which creates a sense of community. Thus, IDUs are more at risk of getting infected with HIV.