When you look at the infection rates and total number of COVID-19 deaths in California, Oregon, and Washington state, I think you have to reach the same conclusion...
In my opinion, millions of West Coast residents had robust immunity to COVID-19 before it officially arrived in the USA in January 2020.
My own theory is that the four strains of coronavirus that cause the common cold confer some level of immunity to COVID-19.
When I moved to the West Coast about 25 years ago, I caught two terrible colds that were unlike any respiratory infection I had ever had in the Southeast or Midwest USA.
In retrospect, the onset and the symptoms of those two colds were identical to COVID-19.
Bottom Line - the number of deaths from COVID-19 and seasonal influenza on the West Coast are almost identical.
That sort of medical outcome must have a clear empirical basis.
“My own theory is that the four strains of coronavirus that cause the common cold confer some level of immunity to COVID-19.”
why? different cold viruses don’t confer immunity for each other and the same is true for the different influenza viruses ...