Hypocoagulability
Hypocoagulability is one of the symptoms presented in the branch of traits affecting the blood system in both Simian Flu and Shadow Plague. It causes significantly reduced ability of the blood to clot, which makes many patients bleed out. It will often cause death through exsanguination.
The Shadow Plague variant of this symptom is much more passive, with many of its infectivity and lethality stats much lower than its counterpart in other plagues, though it requires less DNA and serves to unlock other similar but slightly more severe symptoms in Shadow Plague, such as those that cause hemorrhaging.
In contrast, Simian Flu's version of this symptom is much more severe and lethal, and it requires much more work to find a cure, although it requires much more DNA points to evolve.