That's a very odd virus, but the idea is intriging that you have something that tells you when you hit the halfway mark.

As cover art goes, this is interesting but not necesarily very eye-catching. I'd put a little more emphasis on the forehead circle, and maybe save the long blurb for the back cover. Unless this is the back cover; in which case, it's an excellent design.

Meanwhile, the story concept sounds brilliant and really ocmpelling, and I can see about a million directions you can go with it. I'mma go read it now...