I used this method to keep my disease longer:
when you start, keep playing until you can buy drug lvl1, then keep it until the vaccine starts, then upgrade to the next three.
on mission seven in the breifing it says "your best bet is to find the man who looks likes hes beinb protected"..i aint sure if thats the exact line..but it says beinb...
 "Great Game 1/5"){kind=icon}
 "CycloManiacs"){kind=icon}
 "Wake Up the Box"){kind=icon}
 "Pandemic 2"){kind=icon}
 "Tactical Assassin Substratum"){kind=icon}
 "Hit The Jackpot 2"){kind=icon}
 "Orchestrated Death"){kind=icon}
 "StuntPilot"){kind=icon}
 "Ratmaze 2"){kind=icon}
 "Saboteur"){kind=icon}
 "Kongregate Chat"){kind=icon}
 "- Music in Motion -"){kind=icon}
 "Arcane"){kind=icon}
 "Big Maze Game"){kind=icon}
 "Sonny"){kind=icon}
 "Sketch-It"){kind=icon}
 "The Torture Game 2"){kind=icon}