Herd immunity? Assuming such a thing can exist for Covid and it doesn't mutate every season like influenza.

Do we know it won't mutate? I was under the impression this was unknowable at this point.

There are already several mutations in circulation, so we know it does mutate. The questions remaining are:

* how much does it mutate?

* does exposure to one mutation lend immunity to another mutation?

* does exposure to one mutation lend immunity to the same mutation?

Herd immunity is commonly not well understood in my opinion by the general public. All it means is the point where the spread is no longer “viral” — as in for ever person that’s infected, that person infects less than 1.0 people. People still get infected, die, etc.

Higher the true R0 value for the virus, higher the threshold for reaching herd immunity and the eventual point the infection rate reaching 0.0; globally, without a vaccine, very possible corona will continue to exist years, if not longer.

> People still get infected, die, etc.

Yes, but fewer of them, which is the point.

We've already proven you can go from one case to worldwide pandemic in 3 months. So all it takes is one case somewhere in the World, and you'll never be able to reopen borders.

Now if a fully functional vaccine is developed, that'll of course change things. But there's no guarantee one is possible, so only time will tell.

One known case. There is definitely some time between when it first infects a human and the point at which time humans notice it... especially when:

* most cases are asymptomatic

* most people with respiratory infections (outside of a known pandemic) are never tested for anything

* most people who are tested for infections are tested with standard panels, not studied for novel viruses