A Closer Look at the Spread of Corona Virus (Covid-19)
Throughout the world
There are several sources that track and provide statistics
on the spread of Corona Virus in the world and the U.S. A survey shows the statistics provided by the
New York Times to be as cogent and timely as any of the data out there. These links are updated every day, and
several times each day to provide nearly “up-to-the-minute” statistics on the
spread of the Corona Virus.
For the U.S.
For the world
These links provide for a more detailed, but necessarily
anecdotal, analysis of where each country is in its path with respect to the
pandemic. A cursory look at total cases
and total deaths paints too simplistic a picture, and implies that the spread
of the virus is somewhat linear in nature.
In fact, the spread is exponential, as can be seen by closer examination
of the number of cases occurring in any country over time. The exponential nature of the spread of the
virus is evident from many of the country virus cases versus time graphs.
It is to be noted that the data we are looking at is not
exactly pure, since it is subject to political considerations such as accuracy
of reports from totalitarian countries, efficacy of testing in some countries
and other uncontrollable factors.
However, it is the data in front of us.
The number of cases in the historical model for past
pandemics is relatively flat for a few days, then rises rapidly and exponentially,
and then flattens again as remedial actions mitigate the spread of the virus. A
look at what is happening in individual countries with respect to Corona Virus,
allows us to form some opinions and draw some conclusions.
According to the New York Times, China as of March 13, has 80,815
cases of Corona Virus, and 3,177 deaths, for a 3.9% mortality rate. China is where the Corona Virus started, and the
Chinese occurrence curve is classic in the sense that it looks just like it
should. The spread of the virus in China
started slowly on January 22 for about 6 days, rose rapidly for about 18 days,
then started to “flatten out” on February 15.
It has remained flat to the present time. Deaths from the virus in China lagged the
number of cases by about 10 days, and the death curve began to flatten out on
about February 25.
South Korea, as of March 13, has 7,979 cases of Corona
Virus, and 71 deaths. South Korea is the
only other country where a relatively massive outbreak of the Corona Virus
occurred, and where the exponential case curve has flattened. The death curve in Korea seems to have not
yet caught up with the cases in South Korea, but their low death rate of 71
deaths in 7,979 cases, for a mortality rate of 0.99% is a paragon for the rest of
the world. South Korea’s virus cases
were flat for about 6 days starting February 15, increased rapidly for about 18
days, and then “flattened out” on March 8.
An examination of the curves for most of the remaining major
world countries shows that they are in the rising or “exponential” phase of the
case curves, which have not yet begun to flatten out. This includes the U.S.
Italy and the U.S. are quite similar in the shape and timing
of their data. However, Italy has 17,660
cases of Corona Virus, and 1,266 deaths (7.2% mortality rate), as of March 13,
and the U.S. has 2.030 cases and 41 deaths (2% mortality rate).
For both the U.S. and Italy, the case vs time curve was flat
until about March 4, when it went exponential.
If we can infer by analogy to China and South Korea, we can expect the
case curves for both the U.S. and Italy to start to flatten out after 18-20
days, or about March 22-24 time frame, and the death curve to flatten out about
10-12 days later in early April.
Obviously, there is a lot behind the data we are using, not
only in the accuracy of data from China, but also the efficacy of the health
measures and competency of the countries involved. But as more information
becomes statistically available, it should allow us to spot such general trends
as posited in this little study.
The world is certainly aware of the danger of this Corona
Virus and is expending considerable resources to mitigate it and keep it
contained. We probably have collectively
over-reacted, as is human wont, but this is better than the obverse. Being cognizant of age susceptibility, avoidance
of crowds, social distancing and hygienic measures will help in abating the
spread of the virus. Weather might also
be an ally, helping to decrease the effects of this pandemic, particularly in more
equatorially proximate climes as the weather gets warmer.
Ray Gruszecki
March 13, 2020
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