Zona is an organization located on the Hawaiian island of Moloka'i. Run by a rich and powerful man that cares little for the people stuck outside in the apocalypse.
According to Doctor Merch, after the apocalypse, members of Zona created an experimental vaccine to the zombie virus. It worked at first but the vaccine started to fail and vaccinated people started turning into zombies. The leader of Zona has also been vaccinated, but now his vaccine is also failing. He is looking for a cure to avoid turning into a zombie.