[zh3]

Long conjectured, some disillusioned uni student with the latest tech combining the R number of measles withe the lethality of ebola (and a dash of HIV on the side).

As a twist, "The giving plague" by David Brin is an interesting (short) take on it.

[trinovantes]

If it's too lethal, it would probably kill all its carriers before spreading too far

I wonder if anyone's ever calculated the optimal parameters for a disease to end humanity

[erik_seaberg]

There’s a game about this: https://en.wikipedia.org/wiki/Plague_Inc.

[humanrebar]

It doesn't have to kill anyone. Just sterilize the young.

[mcswell]

Or it could kill off only males (or only females). There is at least one SciFi story based on that premise.