Or you could just play the original Pandemic https://www.newgrounds.com/portal/view/360724

I think that's one detail that this analysis glosses over is that you design the virus to mutate and develop lethality. So initially, it's just like, oh, another common cold, but then once it's infected a large number of people, then it mutates and starts being lethal.

By definition mutation is a random phenomenon, so there's no telling what could happen. But the most likely outcome is the virus loses all efficacy, just as we have a lot of mutations happening within us but they usually amount to nothing (otherwise we would've had a few generations of "X-Men" already).

Madagascar will be safe