Diseases normally evolve toward increased spread by reducing lethality because they don’t have a superpower like Covid2019′s ability to spread while the carrier is asymptomatic. I don’t think there’s much evolutionary pressure on this disease toward lower severity. Even if we do a good job of enforcing shelter-in-place in populous areas, there will be hidden reservoirs until we reduce the number of new cases in connected communities all the way to zero.
The normal evolutionary pressure works because there’s some variation between different strains, and whichever variant can reach the most people comes to dominate. With a normal infection, once everyone is aware, you can quarantine people with evident symptoms and thus squelch the spread. Any variant that has milder symptoms has a better chance of spreading and becoming dominant. Covid2019 already has the ability to escape surveillance if there’s any of it in the population, so a less lethal variant doesn’t have a selective advantage.
Diseases normally evolve toward increased spread by reducing lethality because they don’t have a superpower like Covid2019′s ability to spread while the carrier is asymptomatic. I don’t think there’s much evolutionary pressure on this disease toward lower severity. Even if we do a good job of enforcing shelter-in-place in populous areas, there will be hidden reservoirs until we reduce the number of new cases in connected communities all the way to zero.
The normal evolutionary pressure works because there’s some variation between different strains, and whichever variant can reach the most people comes to dominate. With a normal infection, once everyone is aware, you can quarantine people with evident symptoms and thus squelch the spread. Any variant that has milder symptoms has a better chance of spreading and becoming dominant. Covid2019 already has the ability to escape surveillance if there’s any of it in the population, so a less lethal variant doesn’t have a selective advantage.
My understanding is that asymptomatic spread is pretty common.