Soul Stealer

The Frenzy, so we call it. Made a human into a beast. Dead no doubt and ravenous for flesh. Once the victim was consumed they hunted for more blood, no one knows why, but they only feast upon the living. You must know, there is two kinds of victims. The Seeker, whos red piercing eyes can see the heat of the living hundreds of yards away. And the Sprinter, whom has black eyes with no abilty, but can move faster then its Seeker brotheren. They communicate in a unknown form. The Seeker finds its food and the Sprinter hunts it. Both feed upon us, and need us to live. And can only hunt at night, for the sunlight blinds their eyes temporailly. Artifical light has no effect.
This consumed the human race and took a eigth of us. Until a vaccine was made. Unfortunatly, the affects of the vaccine are not permanent. The victim, if biten yet not devoured must take the vaccine to live. But if biten again, and no vaccine. The victim suffers a unlucky death, then rebirth into the beast.
It kills, then brings us back. We call it The Frenzy because the beast can run faster then a olympic sprinter, and jump as high as 6 feet from the ground.

This is the story of a surivor decades after the breakout.