Following in the aftermath of Operation Black Eden, Nathan Hale's body was further mutated from pure Chimeran DNA and his final encounter with Daedalus. The mutated Hale was killed by Joseph Capelli and his body was later extracted by SRPA. Malikov examined Hale's body and soon discovered a unique protein in Hale's blood which he isolated it and successfully cultivated into a vaccine that is truly capable of eradicating the Chimeran virus. Apparently, the Hale Vaccine was produced on a large enough scale for distribution to the surviving human population.
The vaccine was also compatible with Sentinels, allowing them to revert back to their pure human state. They would then live on without any trace of the virus or almost all of its effects, thus removing the need for inhibitor treatments. However, this meant that the downside of doing so, would be the loss of their enhancements due to the virus, such as superhuman strength and regenerative abilities. The only known effect of the virus retained by humans who were formerly Sentinels are their gold-colored eyes.
Infected subjects injected with the vaccine are known to feel weak temporarily, due to their Chimeran cells being attacked.
- The Hale Vaccine is likely an explanation for why human survivors have begun to use Chimeran Sym-Bac fluid as medication, reducing the number of human casualties as seen in Resistance 3, and can be observed in human settlements in Haven and Mount Pleasant.