The opportunities to mutate depend on the number of infections, and on the immune response of the infectee. Due to deaths, naturally-conferred immunity, and vac

The opportunities to mutate depend on the number of infections, and on the immune response of the infectee. Due to deaths, naturally-conferred immunity, and vaccine-induced immunity, there just aren't those opportunities anymore, here in the US and especially California. A large fraction of us have already tested positive, or been exposed and infected, even if we have not tested at the time we were infected. The fraction of people that are either immune, or able to easily fight off the infection due to healthy immune response, is now sufficient to lower the overall level of population infection. The fraction of people who are susceptible to serious, long-term bouts with the virus is small and heading smaller. Very much unlike the beginning of the pandemic.