Re: YES!!! It is here. Phase II vaccine trial for Her2 3+
My best advice is exercise. Not only is the benefit from aerobic levels shown to reduce recurrence of cancer, but it also helps with depression.
Force yourself to get out and try walking, jogging, hiking, bicycling, running, aerobics class, swimming or anything else that gets the heart rate up between 45% - 60% of your maximum heart rate.
You can google studies on METs (a measurement of breath).
I feel for you on the depression. Start looking for little things that give you pleasure: music, art, dance, writing, socializing, movies.
Medications can help, but fight depression on all fronts is how I feel.