Start a new game and choose the Necora Virus on normal.
Choose any mutations and any starting country.
When the game begins save up 50 DNA points then buy the following:
You'll get noticed and they'll start work on a cure, don't worry just save your DNA points until the cure is 90% complete and allow any symptoms to mutate.
Once you hit 90% of the cure unlock any remaining symptoms you need to, to create zombies which is called Cytopathic Reanimation.
Enhanced Sensory Integration
Temporal Lobe Manipulation
Return to the game and wait you'll get the people are turning into zombies message followed by the vampire bat message after that appears the achievement pops.