Cross-Reactive Immunity is something I left out in my previous newsletter on why some people don't contract Covid.
When someone has been exposed to other viruses which have fragments similar to the Covid virus, the body can retain a memory from the earlier exposure and re-create antibodies from stored memory.
Since Covid-19 is a coronavirus similar to the common cold virus, we can see how cross-reactive immunity can happen rendering some protection from Covid.
Immune cells for common cold may recognize SARS-CoV-2
That's a pretty smart body you have!
Now that this virus seems as mild as the common cold, can’t you tell us that it is one of the common cold corona that has been modified in the lab but has now gone back to what it was before? (Or something like that.) Wasn’t there some controversy in the beginning about whether it could be proved that it was a new virus?