Then I decided to take a look at the
evidence and the data myself in order to make my own decision. After all, I am a statistician and experienced
data analytic professional. So let's begin.
Did you know that the Corornavirus data is available to anyone?
First of all, in case you did not realize, anyone can download all the Coronavirus data from the European Center for Disease Prevention and Control in an excel
spreadsheet. It is a time series data
file beginning with the first occurrence in China in late
December. This data file gives you the daily number of COVID occurrences and the number of deaths by country for every country in the world. The downloadable data
used in this analysis was additionally augmented with data from other sources including each
country’s population and their land mass (more to come on this).
Let’s answer some key questions, shall we?
What follows is a discussion of a few key questions that can
be answered with the data. It is
important to remember that each country is unique to itself, so things like the
availability of tests, regional practices of social distancing, usage of
medicines to mitigate symptoms all impact the data, thus complicate making
comparisons and drawing definitive conclusions.
Is the United States really on the same path as Italy?
One of the graphs circulating out there that concerned me the most is one that compares the United States to Italy. This graph gives the impression that citizens in
the United States are in for the same fate as the citizens of Italy in terms of the number of positive cases. See below for the graph that has many
worried, especially out on social media. This graph represents a replication of that chart using the same data.
The problem with this bar graph is that it is not scaled
appropriately based on the size of each country. To compare Italy cases to US
cases without making it proportional to our population differences is very
misleading. In fact, the US population
is more than five times the size of Italy as seen in the population chart below. The US population is over 330 million while
Italy is just over 60 million.
Once we adjust this chart for
differences in population sizes, the graph paints a totally different picture.
Another chart being disseminated online, including social
media, is the one seen below showing our cumulative case rate in comparison to
other country’s including Italy as well.
As one looks at this graph it appears that we are on a doomed course
compared to all other nations. Nothing
could be further from the truth as you will soon see.
Similar to the bar chart comparing the United States to
Italy, this data is not represented on a scale relative to the population of
the country.
The same data is shown below represented on cases per 100,000 population.
The same data is shown below represented on cases per 100,000 population.
When scaled appropriately, the United States compares very
favorably with other countries. Note the
data is current as of March 21, 2020.
Both of these charts must be put in perspective. In general, you would expect countries with
larger population to have more cases, all other things being equal. But to present a narrative that we are on the
same path as Italy, is irresponsible.
All that was required was an adjustment of the figures to represent
cases on a per 100,000 population basis.
I find it very alarming that some media are presenting the data in such
an irresponsible manner.
Data Limitations—number of
confirmed COVID 19 cases
Another major concern I have with respect to the data being shown
is the issue of accurately trying to show and predict positive COVID 19 cases
and make comparisons between countries based on case data. The
key issues in terms of making accurate "case" comparisons across countries are:
- availability of testing kits for running tests
- access by every citizen to get to a testing facility
Because the above two factors can vary across countries, the
number of cases could be understated until the testing kits or access to tests
“catch up” with unconfirmed cases. In
the United States for example, testing kits have been in short supply at the
start and there are many areas (as with any country) where individuals of
lesser means may not have easy access to transportation to get to a testing
facility or the monetary means to be tested.
As such, I have shifted to use the metric related to COVID 19 mortalities or deaths and not cases. The charts below focus on this metric, with the baseline being at the first death for each country.
As such, I have shifted to use the metric related to COVID 19 mortalities or deaths and not cases. The charts below focus on this metric, with the baseline being at the first death for each country.
So what do the mortality curves look like?
So, what does the incremental and cumulative death figures
on a per 100,000 population basis look like 21 days out since the first occurrence
for the US? The mortality charts below
show our data.
Incremental US mortality rates:
Cumulative US mortality rates:
On their own, these charts are not overly meaningful. So, what do the mortality curves look like for the other
countries and in comparison to the US?
As the charts below reveal, at this time, we are in a favorable position relative to other countries. These line charts compare the US with Canada, Netherlands, Japan, France, South Korea, Italy and Iran all relative to each countries population. But, please keep in mind, anything can change in a moment’s notice. Nothing is constant here.
As the charts below reveal, at this time, we are in a favorable position relative to other countries. These line charts compare the US with Canada, Netherlands, Japan, France, South Korea, Italy and Iran all relative to each countries population. But, please keep in mind, anything can change in a moment’s notice. Nothing is constant here.
Incremental mortality rates:
Cumulative US mortality rates:
What about China's Mortality Curves?
Incremental China mortality rates:
Cumulative China mortality rates:
The life-cycle of the virus
It would take just one super spreader or a major breach in
hygiene to totally change our trajectory.
That is why the tight controls are in place at the moment in the US. And, why the President's team is reluctant to
make predictions. We are still just too
early in the cycle. Anything is possible.
So the question begs, how do we compare to the China virus
graphs? Do we have another two months,
two weeks, or two days to go? Where are
we in the life-cycle of this thing?
To answer this question and assess where the United States and
other countries are relative to China’s life-cycle, I have decided to overlay the
“China incremental and cumulative mortality curves” on top of the prior two
charts showing the same for the US and other countries.
NOTE: When examining
the charts below, the Y axis is not to scale for China but only the X axis to
understand the time element of this virus.
Incremental mortality rates:
Incremental mortality rates:
Cumulative mortality rates:
As these graphs show, China’s incremental deaths per day
peaked in deaths at about 34 days following the first reported death. Following that point the cumulative curve
begins to flatten. If the data maintains
it current trends, it appears that Iran and France are also about to peak. As
more data is reported we should know if this holds true.
Italy’s virus life-cycle has not
matured fully nor has Spain’s. Which is
alarming given the steepness of their curve.
Differences by country—how
has public policy impacted the depth and length of virus impact?
How did China get a strong hold on the Virus so quickly? Why is Italy’s trajectory so steep? What did Japan and S. Korea do to
keep their mortality curve relatively flat?
Below are just a few of many facts that point to these differences:
Below are just a few of many facts that point to these differences:
- First of all, we must remember that China is a totalitarian government. And, as such, they quickly imposed very strict enforcement on their citizens by tracking their every movement via close monitoring of their every step and purchases. To fully understand the extent to which the government monitors their citizens now and prior the virus, I advise you read the article by the AmericanAssociation for the Advancement of Science. Regardless, this tightening of control certainly assisted in quickly getting this virus under control in China. And, flattening out the mortality curve quickly.
- S. Korea was quick to move based on their experience with the MERS virus several years back. This made them ready to scale quickly as also reported by the AmericanAssociation for the Advancement of Science. They even send text message reminders to those that are "positive" regarding hygiene.
- Italy and some of the other European nations have been criticized as being slow to respond. For more information on this see one can read the article by CNBC.
Does our mortality rate to date look favorable compared to other
countries?
At this point in time the worldwide
death rate of confirmed cases is at 4.4%.
This means of all confirmed cases, 4.4% result in death. However, we know this number is
overstating the rate since not all cases are being reported. Why is that?
- Many people do not have symptoms severe enough to cause them to go to the doctor to be tested;
- Some lack the means to be tested; and,
- Some just do not like doctors.
So, what is the real number?
2%? 3%? We will never truly know. But we do know it
is less than 4.4%.
For America, the death rate at day 21 (since our first case)
is at 1.27%. This is about 70% less than
the national average and among the lowest of all nations as seen below at the
same point in time.
But unfortunately, we will not end up this low. We will end up higher than this when all is said and done.
How do we know this?
We know this based on data from other countries. As time progresses, the rate only increases. China, for example, had a death rate of 2.19% at day 21. At day 69 (the end of their cycle) their final death rate was 4.00%. This is an increase of 83% from 21 to 69 days. So, using this figure to index up our rate we can project our death rate will go from 1.27% at day 21 to 2.32% (1.27% X 1.83) at day 69. Again, this is assuming it makes sense to use their data to make US projections. But, what else do we have to use?
How do we know this?
We know this based on data from other countries. As time progresses, the rate only increases. China, for example, had a death rate of 2.19% at day 21. At day 69 (the end of their cycle) their final death rate was 4.00%. This is an increase of 83% from 21 to 69 days. So, using this figure to index up our rate we can project our death rate will go from 1.27% at day 21 to 2.32% (1.27% X 1.83) at day 69. Again, this is assuming it makes sense to use their data to make US projections. But, what else do we have to use?
And keep in mind, with this number, we could extrapolate the
number of beds and respirators we might need going forward. A figure we definitely need to quickly get a handle on future demands of the health care system.
Are there other factors impacting our ability to make predictions?
As mentioned before, It is important to remember that each
country is unique to itself, so things like the availability of tests, regional
practices of social distancing, usage of medicines to mitigate symptoms all
impact the data, thus complicate making comparisons and drawing definitive
conclusions.
Population density
matters
Another major variable that affects the spread of the virus within any given country is the population density of that country or city. The more dense the population, the more rapidly a virus can spread if tight controls are not imposed. The table below
shows the differences in the land mass for various countries relative to their
population size. Given this, one needs
to applaud S. Korea and Japan for maintaining such a low occurrence and death rate.
And, in case you did not realize, the population density in New York City is 67,000 people per square mile. So now you understand all the concern by NY Governor Andrew Cuomo.
What about other
factors?
The demographics and overall health of a population will also likely play a role in how quickly a virus can and will spread and result in different morality curves. Below is a table showing the smoker penetration, median age and overall health score for the various countries. As we can see there are vast differences in these data by country. How that impacts each countries mortality curve is hard to say at this time.
How does this virus compare to deaths caused by
pneumonia and the flu?
To keep things in perspective it is important to remember
that almost 60,000 Americans die every year due to the flu and pneumonia combined.
That is an astonishing number. The Coronavirus, worst case, will most likely take
the lives of around 6,000 Americans (assuming no changes in trends from what we
are observing today).
Summary
In summary, I think we can all agree that America is doing a good job
at keeping this pandemic under control. All the measures put in place appear to be
working. Within another week, as more data becomes available, we should be able to determine our fate. But so far we are looking good.
So, let's keep doing what we are doing. We are almost there. We have almost made it. Let's keep maintaining our social distance,
limiting our outside activities, washing our hands, and stay safe and healthy.
When will the next update be?
We plan to update this report on Monday March 30th.
And, at that point in time, we should have a good sense of where we are headed and what our true needs will be. And, if any other data has shifted.
To your health,
Perry D. Drake, PhD
and Rhonda Knehans-Drake
________________________________________
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Sources
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