Surviving what we now call hell

When America and Russia go to war.
They dropped down the nuclear bomb.
In the heart of America.
Unknowingly a virus soon caught on.
Affecting all Americans.
Only some immune to the virus, leaving the to survive.

But soon enough the strong virus passes through the world.
Affecting All seven continents.
Barely any survivors left, but still some are.
But whoever does survive won't make it in the knew world.

Called hell.