I assumed from the title that it would be a timed goal rather than an inevitable death sentence.
I actually like this a lot as an end-game thing, it’s already been established that everyone is “infected”, but it’s asymptomatic until you die (either that, or that’s the reason the “flu” is so incredibly pernicious).
There could be a time limit (but one only very successful characters would hit, like several months) where the infection becomes acute, and you’d need to race to recover a cure before it does you in.