The tests showed that zombies also eat cheese. That's just perfect, because humans may not fear them anymore. Deliver the slab of cheese to the zombie and feed him.
Didn't you know, that zombies eat not only brains? The last experiments showed, that they also eat cheese. This is not a solution of the problem, but it could work. Deliver the slab of cheese to the subject and make sure it will eat it. Play with constructions and choose the best time to drop the cheese. You won't have another try, so act carefully!