Herd immunity? Assuming such a thing can exist for Covid and it doesn't mutate every season like influenza.
* 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?
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.
Yes, but fewer of them, which is the point.