Maybe I just worded my post poorly. There are only 7 coronaviruses known to infect humans. 4 of them cause common cold, 1 causes MERS, 1 causes SARS and 1 causes COVID-19 (AKA SARS2).
There are many other viruses that ALSO cause common cold, but they are not coronaviruses. Most are rhinoviruses.
Thanks, that does add up a little better!
As for no immunity to “cold” viruses I don’t know what to think.
I haven’t had a cold in 47 years.