The Flare (virus VC321xb47) is a man-made disease. It is a virus that slowly eats away the brain, and eventually turns victims into blood-thirsty and insane humans who consider cannibalism to be an every day objective. People who get the Flare are called Cranks. Every major city in the world (that has not been wiped away by the solar flares) has a special territory for cranks known as the Crank Palace  The public are led to believe that it was freed from containment by the Sun Flares, but that is not the truth. It was once rumored that the sun flares caused a military container to burst, releasing the Flare. However, it is revealed in The Death Cure's exclusive files, and in The Kill Order, that the governments of the world created and released it as a population control method. This is due to the need to control the general populace during the turbulent times of the sun flares, as well as to cut population, due to the destruction of food resources by the sun flares.
A small percentage of the populations were labelled as Immunes- people that are not affected by the FLARE. WICKED attempted to use the Immunes to find a cure by looking at how the brain of the Immune people react to a certain situations, as well as the physical make-up of the brain of the Final Candidate. People immune to the Flare include Thomas, Minho, Brenda, Jorge, and less than 1% of the Earth's population. Most of the Subjects are immune.