Virus is a 1980 Japanese post-apocalyptic film. It stars some names familiar to me: George Kennedy, Robert Vaughn, Chuck Connors, Olivia Hussey, Edward James Olmos, Glenn Ford.
Suitably depressing. The music is lame, so I'm sorry to see Janis Ian's name attached to it.
Midnight Eye has a lengthy review, saying this:
There are some nice performances all round, and the internal dramas which erupt between the various cast members make for some compellingly solid, if somewhat artificial drama. It's a highly watchable piece of early 80s excess, silly perhaps, but undeniably funSpinning Image says,
I'll say this for this determinedly miserable film, it doesn't do anything by halves