90% sure I read it here.
Female main character, she is a zombie -I think it's zombie. Because she never fed on humans she is not mindless. No name, sorry.
There are several castes of zombies one of which are runners. Her caste is stronger than two others but there is a higher caste to hers.
Humans are in strongholds trying to keep the infection out but there is another wave of infection due.
She comes across 4 or 5 humans traveling back to their stronghold and she goes with them - they would not have made it. One of the people is a high cast zombie his partner is a scientist studying the infection.
The scientist seems to be a bit ethically challenged, but by the end does find a vaccine.
They visit several other strongholds one was overrun by zombies. One had the surruonding forest wired and almost killed her.
I remember something about a rabbit hutch that zombies could use- the rabbits wouldn't freak out at the zombie.
I thought I read this in the last year but I can't find it in my lists.
Tanks, limab
