[estearum]

> If a a virus is so deadly, everything it touches dies soon, it would not spread quickly but die out. If it is very contagious .. but very, very slow incubation time, so it infects the whole world, before becoming a deadly disease ..

This is a made up equilibrium that actually does not need to exist in nature.

Viruses and bacteria can in fact be both extremely, extremely contagious and extremely, extremely lethal.

> If a a virus is so deadly, everything it touches dies soon,

Trivially: you actually can have a virus that kills everything it touches not soon. Nothing in biology or chemistry or physics prevents it.

[kcplate]

> Viruses and bacteria can in fact be both extremely, extremely contagious and extremely, extremely lethal.

Sure, but those two things would tend to work against it becoming a pandemic— unless it managed those two things but also kept its host healthy enough for long enough before becoming lethal to adequately spread it.

[estearum]

> unless it managed those two things but also kept its host healthy enough for long enough before becoming lethal to adequately spread it.

I am clearly referring to this specific scenario. There is nothing in chemistry or biology or physics that prevents it.

[card_zero]

I looked into this once, it depends on how splashy the death is. A virus that made people explode instantly into a fine mist of airborne virus particles could be perfectly adequate for a pandemic (although holding off until help arrives might work even better).