The host dies, in one way or another - generally due to the virus itself inducing an illness that leads to brain death, but there are obviously cases of infectees sustaining an injury that proves fatal. Upon death, the virus "repairs" the host body well enough to regain extremely basic motor skills, and to restore some rudimentary mental function, though not much. They more or less just operate on instinct from there - they aren't people anymore, in any real sense of the word.

[He seems pretty calm about this, but he also doesn't sound uncertain at all; one way or another, he knows how this works.]