The Inca didn't even have the concept of infectious disease, or quarantine. If you want a 99.9th percentile bad outcome look at Black Death Norway. Civilization

The Inca didn't even have the concept of infectious disease, or quarantine. If you want a 99.9th percentile bad outcome look at Black Death Norway. Civilization didn't collapse in the face of 60% of the population dying. These are people without the germ theory of disease, never mind antibiotics, antivirals and the state capacity to seal borders completely and modern hospitals. COVID can be really, really bad without it ever having been likely to be a civilizational or species level threat.