Today’s report on COVID-19 in King County | Sun Apr 19

This daily synthesis of the Public Health data is provided by Will Daugherty of Pacific Science Center.  Thanks Will!

Public Health has updated the data dashboard.  As of 11:59 pm yesterday, April 18, there were 5,172 confirmed cases of COVID-19 in King County, 109 more than the previous day.  There have been 346 confirmed deaths in King County due to COVID-19, 6.7% of all confirmed cases.

The numbers that Public Health reports each day include delayed results from previous days.


The first graph below shows new cases (blue bars) and the 7-day average (red line).  Of the 109 new cases reported today, 77 were confirmed yesterday and the remaining 32 were confirmed in previous days but reported to Public Health in the last day.  We see a definite flattening of the curve with the 7-day average continuing to decline since April 1.  The trailing 7-day average is 98 new cases per day, a long way from zero.  The last time the trailing 7-day average was at this level was March 21 and March 22 when it was 96 and 100, respectively.  Governor Inslee issued the “Stay Home, Stay Healthy” order on March 23.

The second graph below shows the total case count.  With 5,172 total cases as of 11:59 pm yesterday, the compound daily growth rate during the last 7 days has been 2.0%, less than the 3.5% rate during the prior 7 days.  At a 2.0% compound daily growth rate, the number of cases doubles every 34.3 days.  One week ago, cases were doubling every 20.2 days.  Two weeks ago, cases were doubling every 11.5 days. Three weeks ago, cases were doubling every 7.0 days.

The third graph below shows the trajectory of cases in King County with the total number of cases on the horizontal axis and the new cases on the vertical axis.  Each axis is on a logarithmic scale.  Each blue dot represents a daily report.  The dot farthest to the left is the February 28 report.  Time passes from left to right as the total case count grows.  The dot farthest to the right is today’s daily report.  We can see a clear change in the trajectory since March 28, shortly after Governor Inslee’s “Stay Home, Stay Healthy” order on March 23.  Here is a good video explaining the benefits of plotting the trajectory in this way (3:20 mark if you want to skip the intro).

Will Daugherty welcomes your questions and comments.  His email is