A vaccine is a medical term for a drug that is used to prevent infectious disease from establishing themselves inside the body. Types of vaccines include: Killed (weakened or dead microorganisms), Attenuated (To reduce the severity of an infection), Toxoid (made from inactivated toxic compounds), Subunit (creates an immune response) and Valance (immunizes against microorganisms).
A number of vaccines have been developed to counter mutagens.
- "Daylight" is the name of a vaccine developed by Raccoon University professor Peter Jenkins shortly before and into the viral outbreak in Raccoon City. Daylight is considered the most potent vaccine, because it killed all trace of the virus completely.
- Elsewhere, Umbrella produced AT1521; a suppressant that both Linda and Carter had some level of involvement in.
- A third suppressant was developed by the staff in the Raccoon General Hospital's underground Umbrella laboratory. There was only one sample that was made and administrated to Jill Valentine.
- A fourth vaccine was created by the WilPharma Corporation to counter the usage of the t-Virus in bio-terrorism.
All first three of these vaccines failed to be mass-produced due to the viral outbreak, even though the research into what became AT1521 was at least two years old.
A vaccine for the G-Virus was developed in the Raccoon City Underground Laboratory. Code-named "DEVIL", it was used only once; Sherry Birkin was given the vaccine as instructed by her mother to Claire in 1998 to stop G-virus that had been infected her.