The movie was about 2 people trying to escape a research lab or bunker where there was a virus outbreak that made you grow hair on arms and back and go mad ,there were plexiglass containment doors sealing off sections and at one part they were using a flame thrower to keep the mad people back. It showed on M-net before 1990 .it was horror (partly burned hairy zombie like mad people )

I don't recall the effects of the virus, but here's one in which they are trapped in a lab:

Warning Sign (1985)
Wikipedia synopsis:
The movie tells about the outbreak of a virulent bacteria in a secret military laboratory operating under the guise of a pesticide manufacturer. During routine work, a sealed tube is broken, releasing the secret biological weapon. Upon detecting the release of the agent, one of the plant's security officers activates "Protocol One", a procedure sealing all of the workers inside from the outside world, and they are left to wait out the deadly effects. A local county sherif's pregnant wife is that security officer and is trapped inside. With the help of a past employee who is a known alcoholic, the sheriff must fight a government agency and the chemically affected workers to put a stop to the spread of the lethal weapon. The former employee was working on an antidote to the weapon, which the sheriff and his wife plan to create and deploy.

http://en.wikipedia.org/wiki/Warning_Sign_(film)

However, I'm not sure their change is so drastic. At the moment, this is the only film that I've thought of.