Depression is definitely difficult to cure, but also difficult to apprehend when it happens to other. I have been witnessed depressed students during the last couple of years, and trying to help to go through is very hard (especially when we have no education in psychology). I am always scared to say the thing I should not say (not on purpose of course)...
Somewhat, this is the disease of the century (together with backaches), and even more an indirect disease originating from the pandemic.
Cheers!
Seeing that most medications used to treat patients who are depressed could make them go back into the depression state as time goes on is one fear. It might be the disease of the century but I do not think the scientific medications available have proven to cure it completely, and psychologist struggle to get patients to come back to themselves.
In all this my concern goes to how a person could become depressed just by staying consistently with depressed people? Do we say that Depression is contagious?
As you said, the problem is the "after-cure". Those people are left alone, and this is where falling again in the depression spiral may happen.
I don't know whether we say this, but I would not be surprised that the environment plays a huge role.
Cheers!