Stare can never be used in Italian to form the passive voice. Those who speak Spanish should pay attention to that. What is possible in Spanish, is never possible in Italian. The passiv voice in Italian is formed with essere, in case we want to describe the result of a process or with venire, in case we want to describe the process itself. In English there in no distinction between these two kind of passive voice, at least there is no special verb to form the passive voice of a process. If it is important to distinguish, we can use the continuous form. The continuous form describes always an action / event as something in the process of happening.