Ua means flower of death in Swahili which is shown in the anime as those infected by the Ua virus have a light blue/ purple flower mark on their bodies and the fact that not many people survive it. It is a biological weapon of mass destruction that kills infected victims to die within twelve hours. It was used in a terrorist attack in Shibuya. Which caused Oosawa Kenji to develop an anti virus.
Borners EditBorners are people who have been infected with the Ua virus and manage to survive. As a result, their bodies mutate and they revive unusual powers, it seems to do this by creating another organ. This gives people special abilities as Hakko has the ability to inflict brain damage using only her voice, while on the other hand Yunyun did not receive any special ability.
When someone becomes a borner blood vessels surface leaving a flower pattern mark, in order to suppress the virus borners require medicine or they will die. The terrorist organisation Snake uses this in order to keep a leash around their borners.
These individuals were infected with the Ua virus who survived before the advent of the anti-virus. The unblooms have flower patterned blood vessels . They do not gain any special ability but they do become very vulnerable to UV rays, sunlight, and outside noises.