What's the Chance Coronavirus Will Kill You (or Me)?
I'm a male pushing 70, and I would prefer that the Coronavirus not kill me (God will take care of that soon enough).
So what do we know about the pathogenesis of Coronavirus and its lethality?
Coronavirus is a family of constantly changing viruses that can cause a variety of illnesses ranging from the common cold to a very severe flu-like disease. Although it is not itself an influenza virus, the disease it causes cannot be distinguished from influenza without testing in the lab ( a case of parallel evolution?).
Like most viruses, it is constantly mutating and trying out new variations. If the new mutation only results in a common cold-like illness, no one will notice it. But if it causes a fatal illness, then it will rapidly come to people's attention. Since the first victims we learn about are those who are severely ill (including many deaths), it initially appears that the virus is catastrophically lethal. Almost always, though, that is not the case, and as more is learned, the initial severely ill victims are seen to be the visible tip of the iceberg, with most cases actually being of only mild to moderate severity.
What makes this particular virus severe, and how does it kill you?
1) The virus has to get inside your cells in order to do its work. Covid-19 has a mutation that allows it to attach to a cell easily and firmly, so that is highly infectious, from cell to cell, and person to person.
2) Once inside the cell, it is highly efficient at replicating itself by suppressing the cell's own processes, and redirecting them towards viral replication.
3) At this point, a race begins between how much damage the virus can continue to cause, versus the capacity of the body to tolerate the damage and fight the virus off.
4) Since the virus is in the process of destroying your lung tissue, and thereby diminishing the amount of oxygen that gets into your body, your ultimate survival is affected by your "pulmonary reserve" (a combination of how much damage your lungs can tolerate, and how well your body can handle a decrease in oxygen).
5) In the end, it is up to your immune system to fight off the virus. Conditions that have weakened your immune system (including simple old age), will increase your vulnerability. In some cases, your immune system is "normal", but still unable to mount an adequate response in time (due to the individual variability of our immune systems). And sometimes, your immune system will overreact, and go on to cause even more damage rather than limiting it.
In the end, there are too many unknown factors to predict who will die in any given case. But general predictions can be made: you are more likely to die if you are elderly, (?male), have diminished lung capacity (smoking), are out of shape, and have underlying conditions that have already weakened some of your organs (especially your heart) and/or your immune system.
If, as is looking more and more to be the case (at least at this time), Covid-19 will end up acting like a very severe flu-like illness, then after a (unfortunate but bearable) wave of deaths (mostly of the elderly), normal life will resume.
Sameul Fistel, MD is a retired physician (pathologist) and scientist.