The OC43 coronavirus offers a model for where this pandemic might go. That virus also gives humans common colds, but genetic research from the University of Leuven in Belgium suggests that OC43 might have been a killer in the past11. That study indicates that OC43 spilled over to humans in around 1890 from cows, which got it from mice. The scientists suggest that OC43 was responsible for a pandemic that killed more than one million people worldwide in 1889–90 — an outbreak previously blamed on influenza. Today, OC43 continues to circulate widely and it might be that continual exposure to the virus keeps the great majority of people immune to it.
I think they mean we get it as children, develop a URI, and maintain resistance by re-posture.
Have to wonder what happens in one’s 80s though and what interesting long term problems might be due to OC43.
Polio was famous for being relatively harmless if acquired very early.