The Cure is humanity's last defense against a plague.
Once a plague becomes spotted, cure development will begin shortly after. Plagues can be spotted due to symptoms, increasing in chance of being noticed when severity rises. If cure progress is at 100%, development teams will rush to infected countries and begin to cure the infected. Once all of the infected have been cured, the game ends. Delaying the cure is very important (evolve Genetic Hardening 1 and 2 to slow research, and evolve Genetic ReShuffle 1/2/3, or evolve stifling symptoms such as Coma and Seizures to further delay research, or make the plague deadlier to kill off valued research contributors). Warnings will be issued when cure development has reached 25%, 50%, 75%, 95%, and lastly, 100%. Even if the cure has been completed, evolving a trait that increases the work that is needed to cure (Such as Insanity or Genetic Reshuffles) will still setback cure progress, allowing the plague more time to eradicate humanity.
Being a microscopic robot, the Nano-Virus can become immune to modern medicines making a conventional cure ineffective. What takes place instead is the Cure Broadcast, which it designed to activate the built-in off switch. What makes the Cure Broadcast truly different is the fact that it starts at the beginning of the game. While the cure meter rapidly builds up if left unattended, the Nano-Virus has much more options to delay the broadcast.
On its own, a Necroa Virus is easy to cure as it lacks many cure delaying symptoms and abilities and inherently requires less time for a cure to be researched. Once zombies have been created, however, this changes. Since zombies are already dead, zombies cannot ever be cured and can continue consuming healthy people and turning them into new zombies even after the cure is fully developed.
In the Simian Flu DLC, the cure is instead developed by Gen-Sys, the company which developed and accidentally released the virus. Once they admit that they created the Simian Flu, they will take over all cure research from governments and use existing data to speed up the cure. They may set up labs near ape colonies to gather data and capture apes, as well as other countries with large ape population. If a Gen-Sys lab is successfully raided by rampaging apes, the cure progress will take a noticeable hit due to lost research.