There is a random event that can appear and you'll see a pop-up for "London Olympics Mystery".
Some time after this another pop-up may appear "London Olympics Back On!" (It does not happen every time)
At this point if you haven't purchased Drug Resistance 1, do so now.
Shortly after purchasing Drug Resistance 1 you will get a final pop-up "London Olympics infect UK!" and earn the achievement.
If you don't purchase Drug Resistance 1 you will see that the Olympics were a success, good medicine stopped the disease spreading.