This is an old sci-fi horror, at least that is were I believe it would go. The plot of the story goes I believe it take place in some bio-pharmaceutical company,or research lab. They are testing something and the workers become infected. They become wild savages, not zombies. There is a woman who is pregnant and for some reason the virus does not affect her

28 weeks later?

It's 1985's Warning Sign with Kathleen Quinlan and a very respectable cast.