This is a follow-up to my earlier posts where I began to track the World Health Organization’s COVID-19 daily situation reports.  I have updated the spreadsheet here through WHO’s Monday (April 26) report.

For the last two weeks the number of new cases and daily fatalities globally and in the U.S. have bounced around in fairly narrow ranges with almost flat trendlines.

However, underneath these relatively stable counts there is a significant amount of dynamism with previous hot spots declining and emerging outbreaks in new locations.  For example, in Europe the numbers have fallen roughly in half in Italy and Spain, only to be replaced by outbreaks in Britain, Russia and Turkey.  The same is true inside the U.S. as New York’s numbers have improved while some other states are seeing an acceleration in the infection.  We are probably going to see this churning for a while.

Here are some other highlights and observations:

Testing

Testing in the U.S. has dramatically ramped up in the last week.  After languishing at about 150,000 tests per day for about two weeks, over about 1.3 million tests have been completed in the last five days.  As testing has increased, the ratio of positive cases has declined.  I suspect with the increase in testing we may see a divergence between daily new cases and fatalities, with fatalities falling faster than new cases.

Outbreak Continues to Disproportionately Hit U.S. & Europe

The degree to which the outbreak of COVID is concentrated in the U.S. and Europe continues to be stunning.  As of today, the U.S. and Europe account for about 80% of the total confirmed cases and 87% of the fatalities in the world.  Their portion of the number of new cases daily has fallen from 90% two weeks ago to 65% now.  All of these are, of course, grossly disproportionate to their population.

It is interesting that all the serious outbreaks have occurred in temperate climates, especially with the DHS test results announcing this week that the virus’s ability to live on surfaces is adversely affected by heat and humidity.  That is something that we need to continue to watch.

Outbreaks are Extremely Geographically Concentrated

I have begun to realize that looking at an entire country can be quite misleading because the COVID outbreaks are extremely concentrated in relatively small geographic areas.  These three maps, from the New York Times, of the outbreaks in the U.S., New York, Washington and Italy on a per capita show just how geographically concentrated the outbreaks have been.

Click here to see New York Times maps and tables.

This concentration would suggest that the infection rate in those areas is much higher than the national statistics would reveal.  Recent antibody testing in New York supports that conclusion as well.  This reinforces an emerging picture that the virus is likely both much more infectious and much less lethal than previously thought.

This concentration also begs the question of why areas like New York and northern Italy were hit so hard while areas only 100 miles away have been virtually unaffected.  Is there something unique about these areas that made them susceptible to a bad outbreak or does this mean that once the virus is sufficiently seeded in an area there will inevitably be a serious outbreak in that area?

We obviously do not know the answers to those questions yet, but this trend is something we need to continue to closely monitor because it could greatly inform our policy measures.