Vongspawn virus was the infection created by Zenoc Quah, a fanatical Yuuzhan Vong Shaper, and Darth Maladi, a master of Sith alchemy and high ranking member of the One Sith, that spread out on many terraformed worlds as a result of the sabotaged Ossus Project. The virus caused painful bony growths to sprout from the skin. It didn't affect any Yuuzhan Vong or the Jedi - which made it look like they had organized it. The growing tension eventually led to the start of Sith–Imperial War and the shift of power in galactic society due to the fall of the Galactic Alliance and the rise of the Fel Empire to dominance, albeit a short-lived one. Many infected Vongspawns were left across the galaxy as the result of the plague.