COVID-19 June 27, 2020

Today I had to do something I hadn't done for quite a while: I had to change the ordinate on the graph of new daily cases.  Yesterday's 44,726 is the highest value ever, and my graph only went to 40,000.  I've now bumped it up to 50,000.  With an average doubling rate that is now under 15 days, I suspect I'll have to continue to adjust the graph.

This weekend should be interesting because the daily numbers in this part of the week tend to be lower.  Will they be?  If not, that indicates a growth rate that is so large that it is actually starting to swamp out the very large weekly oscillation. As indicated above, the doubling rate of new infections based on the data beginning June 9 is just under 15 days.  The doubling time has decreased every day this week.  If you look at the new daily cases since June 9 (it's the red data on the graph), you'll see a dotted black curve that represents the best exponential fit to that data.  If the numbers over the next few days don't start to moderate as they should as part of the weekly cycle, then that best-fit black curve is going to get even steeper, and the doubling time is going to continue to decrease.

I've dropped the semi-log axis plot of cumulative infections back in today.  The last seven days are shown in orange and the best fit linear line to that data is also shown.  The slope is 34,753.  That slope represents the number of new infections per day that best fits the data.  Taken with the data above, we can then expect the number of daily new infections to be about twice that in about two weeks, and that's assuming everything just stays as it is now.  So, about 70,000 new cases each day two weeks from now.  Every indication is that this is a conservative number. 

Now onto the death statistics.  The average number of daily deaths continues to decrease, but it's becoming increasingly clear that they are not dropping as fast as would be expected by Gompertz model (shown as red crosses in the daily death chart).  Daily deaths will lag by at least two if not three weeks the number of new cases, so the numbers from yesterday represent the number of people that died from infections acquired in the early part of June.  This relatively slow decrease in deaths mirrors the relatively slow decrease in infections at that time.  It's going to take a couple of weeks before we start to see the average death numbers start to reflect the dramatic rise in new cases.  Even if we locked everyone in their houses today, a spike in deaths is almost inevitable.  This is why politicians that are making policy decisions based on current numbers are three or so weeks behind the curve.  Today's numbers tell you about the mess you are going to be in two or three or four weeks from now and there's nothing that can be done about it.  Policy changes today only show effect three or more weeks after that fact.