bungeejumper wrote:The emerging view is that you can catch coronavirus multiple times, because it mutates rapidly, and because there's no backup reservoir" of resistance to it.
A reputable source for that notion would help, else it's speculation with little value, of the type that naturally occurs when people are operating in an environment of uncertainty.
NB I'm not claiming it is speculation, but that's why I ask for a source in order to clarify.
Looking at case mortality rates across the population as a whole (ie. not age cohorts)...
The mortality rate calculation is obviously highly dependent upon determining the correct denominator (ie. the total number of confirmed cases), else you can (drastically) overstate the mortality rate.
By a number of accounts, South Korea appears to be running the most thorough and comprehensive testing regime of anywhere in the world. Their calculated mortality rate is currently running at 0.72%, vs. the WHO's average rate of ~3.4%, which may well be explainable by South Korea's denominator being significantly larger due to their more through testing regime better capturing the reality of case numbers.
Hence, at present I attribute greater weight to South Korea's rate than that calculated in other countries, where testing regimes may be much less comprehensive such that very many cases will remain unconfirmed, skewing the calculations. I think there's a good chance this is what's currently happening, and that over time, with more widespread and thorough testing, we could see mortality rates converge into the 0.7-1% range.
Clearly, the vast bulk of these fatalities will be concentrated in the upper age cohorts (I did have a distribution but it's out of date so won't quote figures). As to the doctors and other healthcare staff succumbing, there may be a number of factors at work: due to their roles they will likely have had significant and sustained exposure so a large viral load; they may have had impaired immune systems due to working all hours trying to save other people's lives; they may have had underlying issues, diagnosed or undiagnosed; they may just have been unlucky, as some people will be.