COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.

We realize there are many people interested in keeping up with developments around COVID-19.  So please feel free to share this email to any interested parties.  We are praying for an end to this pandemic.


Today (Wed), the message from both NY (the epicenter) and the White House is that COVID-19 is on track to require to undershoot “peak” utilization of the healthcare system.  This is very critical development, because earlier in this crisis, the risk to the country was an overburdened healthcare system, which would lead to first responders to choose which ones to save and leading to needless deaths.  And the other message remains that NY state does indeed seem to be moving through the apex of the crisis and the other side is flattening of case growth, decreasing hospitalization admissions and eventually a tapering of deaths.

NY foremost has been the epicenter of this crisis and still represents 35% of the 435,000 cases in the US.  But, as intensity of the crisis in New York state eases, the key for seeing a decline in overall USA case growth depends upon:

– other cities, counties, states to see COVID-19 curves below NY;
– local governments need to use best practices to contain spread via testing or social distance;
– optimize treatment regimens.

Widespread deceleration of case growth seen across the USA, based on county-level data…
Every outbreak is local.  In fact, in a section of this email, we show how NYC cases spread to surrounding counties.  And because each outbreak is local, we think it is useful to track county-level data, rather than state level.  Our tireless data scientist (Ken) enhanced some of the county-level data (coming from Hopkins) and a few interesting insights emerge (more forthcoming as we further analyze the datasets):

– first, there is widespread deceleration of daily case growth across the USA.  A simple way to measure this is a diffusion chart (below).  As of 4/8/2020, counties representing 51% (of the USA population) saw daily case growth below 10%.  A week ago, this figure was 21%.  So 30% more of the USA falls into this tier.

– second, only Detroit, Philadelphia, D.C., of the top 50 MSA are seeing case growth worse than NYC.  In other words, the curves are already flatter for the rest of the country.  This could change, but this is a good thing.

Diffusion chart: More than half of the USA is seeing cases growth slow to <10%…
Looking at the >3,000 counties in the USA, we grouped their daily case growth into 5 tiers.  The highest growth rate is >41% (2X in 3 days) and the slowest is <5% (doubling every month).

– On 3/19/2020, the plurality of the USA saw case growth >41% and this is arguably the “peak” velocity spread of COVID-19.
– On 4/3/2020, 2 weeks later, the plurality of the USA saw case growth between 10%-19% (15% mid-point), or cases doubling every 5 days.
– As of 4/8/2020, 51% of the USA has daily case growth <10%.  And the green bar (<5%) is now 16% of the population.

We realize this chart is a little hard to read, perhaps we may stack the lines, but the bigger point is the across many counties in the US, we are seeing the benefit of social distance.  This is leading to a nationwide slowing of cases.

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.



POINT #2: Most other major cities outperforming NY.  Doing worse is Detroit, Philadelphia and D.C.
Of the 50 largest counties in the US, 16 of these have daily case growth >10% (which means cases double <1 week).  And these are probably the places to watch for the next major case outbreaks–that is, these are cities large enough (~1mm mostly) that could result in widespread healthcare utilization.

– Overall, of the cities shown below, Detroit, Philadelphia and D.C. are seeing steeper curves than NYC (rebased to day 0 = 100 cases).
– In terms of case growth solely as a metric, topping this list is Montgomery County, MD (Rockville is the largest city) and sits right outside Washington D.C. (we analyze surrounding counties below).
– Next is Cook County, IL with Chicago as the anchor city (20% case growth).  At 490 cases per 1mm Pops, this is far below NYC’s 9,812.

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.



We plot the 3 troubled cities, plus Chicago (because it has #2 in daily case growth) but to improve comparability, we look at cases per 1mm residents.  And the date axis starts day 0 when cases >100.

– If a city is above NYC, that is a steeper curve and means the City is doing worse than NYC. 
– And worst among these is Wayne County (Detroit).  Not far behind is Philadelphia.

The message here is these 3 cities will bear watching over the coming weeks.
 

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.



Perhaps, therefore, it is no surprise the White House is monitoring those cities carefully.  According to a recent CNN article (CNN article), Dr. Deborah Birx, White House Corona Virus Coordinator, recently expressed concerns about Philadelphia and D.C.

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.




County-level data shows how much worse Louisiana fared… but it is a smaller GDP contributor…
New Orleans, LA has been overwhelmed with COVID-19 and the case penetration is nearly 2X NYC.  But the reason we are not as focused on this as a “resource consumer” is that the total county sizes are considerably smaller.  

– NYC has a total population of 8.3mm while the largest counties in LA are 400,000 or so, or 1/20 the size.
– We apologize if this comes across as insensitive.  We are simply highlighting that the economic consequences of these counties is less than Los Angeles, NYC, etc.

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.



Point #3: Another study weather impacts the spread of COVID-19.
A recent study by Tamma Carleton (University of Chicago) and Kyle Meng (UC Santa Barbara) assert that COVID-19 transmission is very seasonal  (Preview of study here and Article summary here).  This is not yet peer-reviewed and was posted on Medrvix.org and it has intriguing conclusions.  The key abstract below:

“We find robust statistical evidence that a 1°C increase in local temperature reduces transmission by 13% [-21%, -4%, 95%CI]….we project that changing temperatures between March 2020 and July 2020 will cause COVID-19 transmission to fall by 43% on average for Northern Hemisphere countries and to rise by 71% on average for Southern Hemisphere countries.”

Basically, the authors suggest that each 1 degree Celsius rise in temperatures reduce transmission by 13%. Their work isolated weather from public health responses, densities of cities and other factors.  And if they are right, the spread of COVID-19 should slow sharply as the weather improves across the USA.

Is weather a factor behind why Los Angeles, San Franciso and Seattle saw flatter curves than NYC?
We plotted the cases/1mm for NYC vs LA, SF and Seattle (day 0=100 cases) and each of those cities had substantially flatter curves.  This is quite impressive.  Granted, this could be the cities were better prepared, had better compliance, better awareness or just got lucky.

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.



But even Texas has fared considerably better.  We know Dr. Birx referenced Houston as a potential trouble spot.  Houston is in Harris County.  And Texas is no small state.  3 of the 10 largest cities in the US are in Texas.

– But notice how much flatter those COVID-19 curves are?  Again, is this weather or was NYC just the unluckiest place.
 

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.




Point #4: NYS and NYC remain passing the apex.  Counties around NYC are worse than NYC now…
We are not writing about NYC and NY state cases today, partly because we realize the data can be lumpy.  But instead, we decided to show you the extent of the COVID-19 spread in the surrounding counties of NYC.  And more specifically, the extent of case penetration.

First, a geography lesson.  Many of NYC workers and families live in surrounding counties.  The graphic below zooms in on the counties surrounding NYC.  Westchester (North), Rockland (NW), Nassau, Suffolk (East) and even further out is Orange and Putnam counties (longer commutes or vacation homes).

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.



We plotted the cases/1mm residents for those surrounding counties below.  We did not ‘rebase’ the cases.  Rather, we plotted this all on a calendar date basis.  And we note the date of the first case in each instance (it might the date of the first 100 cases, Ken would know for sure).

– NYC and Westchester saw the first cases in early March.  
– Nassau, Suffolk, Rockland (commuter distances) saw cases +2 to +5 days later.
– Putnam and Orange (longer commutes, weekend homes) saw cases +10 to +13 days later.

NYC was the first.  So we would expect NYC to have the highest cases per 1mm residents.   Given the extremely high population density of NYC (multiples of other counties), the spread should be much worse.

– That is not the case.  Of the 6 counties above, 5 of 6 have considerably higher cases per 1mm residents.
– The suburbs did EVEN WORSE than NYC.  How is this possible?
– And Orange County, which is not very densely populated and a very far distance from NYC, has more cases per 1mm.

COVID-19 UPDATE. County data shows major deceleration of daily case growth across USA. Plus, another study shows temperature variance impact disease transmission.




To conclude, COVID-19 remains extremely puzzling in its spread and the fact that the spread in surrounding counties of NYC is worse than NYC.  But the good news is that county-wide data is showing a widespread slowing of COVID-19.

And we hope warmer weather does indeed slow transmission.  We realize many are skeptical of this.

Please remain safe and healthy. 

More from the author

Disclosures (show)

Get invaluable analysis of the market and stocks. Cancel at any time. Start Free Trial

Articles Read 2/2

🎁 Unlock 1 extra article by joining our Community!

You are reading the last free article for this month.

Already have an account? Sign In

Don't Miss Out
First Month Free