(Capcom's primary storyline)
Anti-C is a vaccine produced in 2013 for the Crysalid Virus, otherwise known as C-Virus. It was developed by an American institute under US federal oversight, and though it was recognised to only provide limited protection during the vaccine trial, the health crisis posed by C-Virus was deemed too severe and it was mass-produced.
C-Virus is a genetically-engineered strain of Progenitor Virus created by The Family as a next-generation bioweapon. Through 2012 and 2013, the virus underwent extensive bioweapons testing, being covertly shipped to extremist groups around the world. Due to both its engineering and this covert manner of testing, the World Health Organization, while aware of the crisis, was unable to coordinate vaccine trials. This situation changed in July 2013 following the recovery of a blood sample from Jake Muller, an Edonian-American mercenary who had developed a resistance to a C-Virus infection. Muller himself was already a person of interest the previous year, though had been held captive by Neo Umbrella, a paramilitary at the time connected to The Family. The US federal government oversaw the production of this vaccine at an unspecified lab.
Anti-C's first trials took place shortly following the Lanshiang bioterror incident, and may have included victims of the attacks as well as more recent incidents caused by insurgents who had also been provided with C-Virus. Anti-C was found to have severe side-effects on the recently infected, resulting in the deaths of the majority of vaccinated. In those who had already suffered extensive mutation from the disease, death was noted to be immediate in all instances vaccination was attempted. Though these alarming results were identified in the vaccine trial, the severe threat posed by the C-Virus was recognised by the WHO, which believed mass vaccination of the population was essential in lessening its reliability - and thus marketability - as a bioweapon should attacks continue. Due to concerns an antibody-resistant C-Virus strain will inevitably replace the current bioweapon, the UN, through the Bioterrorism Security Assessment Alliance, began tracking Muller in the event fresh blood samples were needed.