Pick Frozen Virus In "Cure" Mode.
Hire Field Operatives And Wait Until The Virus Gets Analyzed.
Get The "Presence of Field Operatives Lowers Infection Rate" And Fatality Upgrades
Once Complete, You Have To Upgrade To The Purple (Or Green) Level Of Research.
(It's Level 2)
Right Next To It, Is Three Field Operative Upgrades That Increase The Amount Of Countries They Can Affect. (Same Color As The Research Upgrade)
Getting All Five Of These Upgrades Netted Me The Achievement.
Good Luck!