Damnednation 2.0

A group of ex-Umbrella researchers are working on a virus that was supposed to boost the immune system. They transported the incomplete but 'harmless' virus to another lab. Someone from that very same group saw its potential and attempted to sell it to the black market, but instead it leaked into the city causing an outbreak. The virus is airborne, but a small percentage of humanity is immune to it. It has a really fast spread rate.

Somehow it was found to have an aerosol type neutralizer that causes the virus to degrade and let the human immune system to finish it off. There's a chance of it failing. The components needed to finish the said neutralizer are scattered in different labs.