It may take way longer than 100 days, but pick parasite and remove symptoms and pick no transmissions.
Wait for it to gain the "Harmless" trait.
Get all resistance to III and wait some more.
By the time it says they are making a vaccine you will have enough to get some transmissions and many of the lethal symptoms.
GG.
I started in the US and got every country infected with some only having a few and withing second the world died off.
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