Prototype Vaccine

The Cure, also known as the Prototypical Vaccine, is currently the only known antigen against the Infection.

Overview
The Prototype Vaccine was developed by NEMEXIS as a possible cure (or at least treatment) against the Infection, though it was stolen before any clinical test results could be proven. Because of that, it is unknown if the vaccine has any Infected at all, especially at the stage it has reached.

The "True" Cure
It is unknown if there really is a possible treatment or cure for the Infection. The virus seems to bypass any natural defences, and no single person has been shown to be immune to the Infection. Especially since the events of Cabin Fever, it is unknown if anyone is invulnerable to the virus, including the Player.

Even if there was a possible treatment for the Infection, the virus' damaging effects seem to be long-lasting, and possibly irreversable. The matter of getting the cure into a victim may also prove difficulty, especially if the virus has undergone a major mutation.