New Plague

The New Plague virus, also called the Blue Flu, or Limit 115 was an infectious disease which rapidly spread throughout the United States in the 2050s, eventually demanding a national quarantine in 2053. The epidemic became the driving force behind the Pan-Immunity Virion project that paved the way for the Forced Evolutionary Virus.

Characteristics
The time of incubation of the virus varies, taking between three to five days. Initial symptoms greatly resemble the classic flu. The Plague eventually worsens, leading to profuse sweating, unexplained contusions and swelling, eventually terminating in massive external hemorrhaging. It may also result in clogged respiration, leading to death through asphyxia. Should anyone survive the plague, they are rendered completely sterile by the virus.

Though the exact method of infection is unknown, the New Plague virus was highly virulent and could be easily contracted in any social situation. The usual methods of controlling the spread of the disease were isolation and containment.

Background
The New Plague virus was actually a top secret military project, codenamed Limit 115. It was a genetically engineered biological weapon developed by United States scientists working under the aegis of the power groups that would later form the Enclave. The intent was to deploy it against China, to sterilize large segments of the population and undermine enemy manpower.

The virus was inadvertently released in 2053, when a group of Chinese infiltrators procured samples of the virus. They were killed in Denver during their escape and the sample containers were damaged. As they were shot in a public area, the virus managed to infect a large number of people. This led to a widespread epidemic that killed an estimated twenty thousand citizens across the United States, with the epicenter in Denver, Boulder, and Colorado Springs.

The virulent nature of the plague and the speed at which it spread led to the first-ever national quarantine of the nation and the closing of borders, as tens of thousands die. In 2055, West-Tek started to develop a cure for the virus, establishing the West Tek Research Facility.

However, despite extensive quarantine measures and research, no cure would be developed. By 2063, the New Plague continued to spread throughout the nation, the death toll fueling national paranoia. The government used the rising paranoia to discourage assemblies, fuel the anti-communist sentiment, and encourage informing government forces of suspected subversive elements.

West-Tek was ultimately unable to develop a cure. Instead, in 2073 the government contracted the company to develop a Pan-Immunity Virion in response to China's aggressive use of biological weapons. Although unsuccessful, the PV Project would lay the groundwork for the development of FEV.

However, the FEV research would leak out in 2077, leading to widespread protests and lead many to speculate that the U.S. government was responsible for the New Plague in the first place.

Behind the scenes
The plot of Van Buren centered around Victor Presper, an NCR scientist, who uncovered the truth behind the virus around the 2250s. He decided to use the potent virus as an agent to cleanse the wastelands and impose his order on the world. He would manipulate ULYSSES into activating B.O.M.B.-001 by releasing Limit 115 in survivor communities, forcing the AI to go into disease control mode (with nuclear weapons). By that time, Presper would be on board the space station and target the nuclear missiles where he wanted them to go.