The Iridian Plague refers to a disease that occurred in the galaxy before the First Order military initiated their assault on Tah'Nuhna, a neutral world located in the Mid Rim, during 34 ABY. It was the doctors of the Tah'Nuhna species who discovered the remedy for this plague. During the First Order's offensive, one member of the Tah'Nuhna contemplated this accomplishment, along with other achievements of their people.
The initial mention of the Iridian Plague within the new Star Wars canon occurred in 2019, specifically in the first issue of the Star Wars: Allegiance comic series. This series was penned by Ethan Sacks and released by Marvel Comics. The disease has roots in the Star Wars Legends continuity, initially appearing in the 2003 video game Star Wars: Knights of the Old Republic.