COVID-19 June 30, 2020

We had a nice little down day yesterday, as expected.  The rest of the workweek should be up, up, up, at least if history repeats itself.

Even though the daily numbers went down yesterday, the 7-day average for daily deaths actually ticked up for the first time in a while.  Is this the start of the anticipated upward trend?  The total number of dead and the daily death rate certainly are showing the divergence from the Gompertz model.  Not unexpected at all, but it's interesting to watch as it develops.  The difference between the data and model tells what could have been if we had done things correctly whereas the actual data tells us how badly we f*cked up.

There was some discussion on my Facebook wall about why it's taken so long for the death rate to respond to the increase in cases.  There's a couple of reasonable hypotheses.  First, the current increase in infections primarily has hit the younger demographics that are less susceptible to complications and death.  The initial peak in deaths had a very strong contribution from the elderly, especially in care homes.  The younger people dominating the cases now are still infected and contagious and they will eventually transmit that virus to the general population.  They just need to take it over to grandma's home.  That process introduces an additional lag.

The second possibility is that the virus is mutating to a less lethal form.  Evolutionary pressure tends to favor viruses that don't quickly kill their host, and our actions over the last few months may be adding to that evolutionary pressure.  The most severe and lethal cases often end up in hospitals where transmission is effectively terminated.  That's the end of the line for whatever virus is the hospitalized person.  Those that are not severe enough to require hospitalization are still out in the wild and can continue to spread their particular strain.

I note that neither of the two hypotheses are mutually exclusive.  There could be an increased lag in transmission and viral mutation.  And, of course, there could be entirely different explanations.  All this is likely to get sorted sometime in the future, but it's extremely hard to tease out the cause in real time.