Why Covid-19 Might Never Go Away
We could get used to it, like the common cold… after millions of deaths
Imagine a glorious planet without the common cold, a twin of earth, its human population just like ours in all ways but one: Nobody has ever had a cold, because none of the more than 200 viruses that cause colds exist there.
Now drop into that world a common cold-causing coronavirus from our planet, one that typically triggers nothing more than a stuffy, runny nose. Novel on this naive twin planet, the virus ravages the elderly population and largely spares the young. Sound familiar? The hypothetical scenario isn’t a sci-fi movie plot, at least not yet, but rather a way to potentially fathom the wildly disparate age-based death rates of Covid-19, caused by the coronavirus SARS-CoV-2.
Most common colds are caused by rhinoviruses, but some are due to coronaviruses. Maybe this novel coronavirus is not all that different from those that cause colds, muses Michael Mina, MD, an assistant professor of epidemiology at Harvard T.H. Chan School of Public Health. Maybe the reason it’s so deadly for older people, Mina suggests, “is really just the complete lack of pre-existing immunity and not having had potentially hundreds of exposures to the virus over the course of a lifetime.”
“I think that’s actually a very reasonable plot… I think it’s quite possible,” says Rebecca Dutch, PhD, a virologist and professor of molecular and cellular biochemistry at the University of Kentucky College of Medicine. Dutch has heard the idea before, and credits it to Ralph Baric, PhD, professor of epidemiology and immunology at the University of North Carolina at Chapel Hill.
“Yes, I’m likely the first one who made this hypothesis,” Baric tells me. He explains: “Four contemporary human coronaviruses all emerged from animal populations 100–800 years ago. All of these viruses are mild childhood illnesses, but can cause severe disease in the elderly as they become immunosuppressed.”
Exploring the hypothesis illuminates how the human immune system works, why it works better in children, and how decades from now, if no vaccine is developed and many, many more people have died, SARS-CoV-2 could circulate routinely in humans much like other common-cold viruses.