The Eternity Cure (Blood of Eden)

In Allison Sekemoto's world, there is one rule left: Blood calls to blood 

She has done the unthinkable: died so that she might continue to live. Cast out of Eden and separated from the boy she dared to love, Allie will follow the call of blood to save her creator, Kanin, from the psychotic vampire Sarren. But when the trail leads to Allie's birthplace in New Covington, what Allie finds there will change the world forever—and possibly end human and vampire existence. 

There's a new plague on the rise, a strain of the Red Lung virus that wiped out most of humanity generations ago—and this strain is deadly to humans and vampires alike. The only hope for a cure lies in the secrets Kanin carries, if Allie can get to him in time.  

Allison thought that immortality was forever. But now, with eternity itself hanging in the balance, the lines between human and monster will blur even further, and Allie must face another choice she could never have imagined having to make.