I'm sure if this theory is popular in NA. but supposedly there are three possible strains of COVID-19 atm.
There are type A, which has been around the world by last winter, mostly found around West coast of USA and Wuhan. The symptom of this one was similar to common flu, more severe, but not significantly worse so not much attention of it was given.
Type A mutated to Type B in Wuhan and also later infected New York... where it becomes more deadly and infectious.
Type B eventually mutated to Type C. in the middle of infecting Europe and alike. It's currently most commonly found in later part of infection in Europe and Asia.
How ever, given you can be reinfected with the same type of virus..... being infected with and have antibody against Type A doesn't mean we are immune from Type B and C, and they have crawl their way back to CA due to traveler from the East coast.
There are type A, which has been around the world by last winter, mostly found around West coast of USA and Wuhan. The symptom of this one was similar to common flu, more severe, but not significantly worse so not much attention of it was given.
Type A mutated to Type B in Wuhan and also later infected New York... where it becomes more deadly and infectious.
Type B eventually mutated to Type C. in the middle of infecting Europe and alike. It's currently most commonly found in later part of infection in Europe and Asia.
How ever, given you can be reinfected with the same type of virus..... being infected with and have antibody against Type A doesn't mean we are immune from Type B and C, and they have crawl their way back to CA due to traveler from the East coast.