[Smallpox, bioterrorism agent]
From those links which I just read, prior vaccination confers some survival advantage, and hemorrhagic smallpox is not a strain selected for weaponization, but a particular clinical manifestation that is genetically predisposed for a fatal outcome. It's hallmark is a low platelet count, i.e. thrombocytopenia which can be caused by less platelet production by the bone marrow, less free platelets available because of consumption in blood clot formation and simultaneous phenomena.
I wish there was as good a book available on surviving bio-terrorism as there is against nuclear attack. If you haven't availed yourself of Nuclear War Survival Skills, I think you would enjoy it immensely. It is so eminently practical that it could be a foundational part of a high school curriculum in general survival skills.