The Last Subject

Barbie Rous is a lone survivor in a world ruled by body-invasive parasites that have conquered most of humanity. Sneaking into her base kept securely hidden from the outside world, Barbie is in possession of a formula that can potentially destroy the parasites within a person and restore their humanity.
Held captive in her base is Kristof Cale, a man infested with parasites. Subduing Kristof and restraining him to a surgical table, Barbie injects the antidote into Kristof, observing him closely as his humanity slowly begins to emerge.
Believing it to be a success, an eager Barbie runs to her radio and sends out a broadcast reporting her findings. Unfortunately for Barbie, she has kept her eyes off of Kristof as the cure fails to work and his parasitic condition accelerates, snapping out of his restraints.
He lunges at Barbie, plagued by the nature of the parasites causing him to tear through her clothes and spread the infection, sliding his cock inside of her pussy. Barbie succumbs to the corruption with Kristof transferring his parasites to her body, snuffing out any hope of a potential cure for their world.