When the V-ACT process occurs within a zombie, the heart begins pumping at an alarming rate, causing noticeable blood seepage in the skin and giving it a crimson shade, while the eyes become white and glowing. The subject's fingers and toes develop sharp claws and an increased muscle mass and movement speed. The subject's level of aggression also increases exponentially from that of the typical zombie, and the typical moans become loud, hoarse roars. When zombies mutate into Crimson Heads, virtually nothing will stop them from pursuing their prey, and will even slice through other zombies standing between them and their prey. As a result, these creatures are extremely dangerous.