If confirmed, this study might explain why so many people can shrug off COVID-19 (asymptomatic). My working hypothesis would be that people with baseline cross-reactive immunity and a strong immune system can easily fend off CV19.
Since older people surely have had the common cold many times, one has to ask why the elderly are having such severe issues with the COVID-19. The answer might be simple: poor overall health including a weak immune system that can is sluggish to rouse itself when something attacks could give CV19 precious extra days to establish itself and wreak havoc.
[emphasis added, excerpts from full interview]
A new study provides evidence that the seasonal colds you've had in the past could protect you from COVID-19. The study also suggests that immunity to COVID-19 is likely to last a long time -- maybe even a lifetime.
The study, published in mBio, is the first to show that the COVID-19-causing virus, SARS-CoV-2, induces memory B cells, long-lived immune cells that detect pathogens, create antibodies to destroy them and remember them for the future. The next time that pathogen tries to enter the body, those memory B cells can hop into action even faster to clear the infection before it starts.
Because memory B cells can survive for decades, they could protect COVID-19 survivors from subsequent infections for a long time, but further research will have to bear that out.
What this study doesn't show is the level of protection provided by cross-reactive memory B cells and how it impacts patient outcomes.
"That's next," said David Topham, Ph.D., the Marie Curran Wilson and Joseph Chamberlain Wilson Professor of Microbiology and Immunology at URMC, who runs the lab that conducted this work. "Now we need to see if having this pool of pre-existing memory B cells correlates with milder symptoms and shorter disease course -- or if it helps boost the effectiveness of COVID-19 vaccines."