Unless the thing you unearthed from the 15 thousands year old underground piece of ice from the north pole is a microscopic parasite that take months to show any symptoms and turn you into a zombie to spread. Then your just patient zero and we're fucked as a specie.
If the incubation is a few months, and it uses saliva to spread, then it's too late. Unless you mean nuking all earth and surviving undergrounds à la Fallout.