Info on the pandemic
Many people have lots of questions about the data surrounding this pandemic. Most of those who are discussing this horrible event, those with a podium, also have an agenda. I wanted to get some basic information out.
The mathematical model of an epidemic….
Initially there is exponential growth and in most countries the growth was between 20-40% per day. the US was 34% per day more or less, hence an exponential growth rate of 1.34. Then when countermeasures are implemented the exponential growth changes and the slope of the new cases passes from >1 to <1. It then increases to a peak and then begins a downward trend depending on what causes the epidemic to subside. Hopefully those "causes" that change the slope are countermeasures to the epidemic, such as
· testing with
· both quarantine and tracking,
· social distancing and
· masks.
Alternatively, the slope would change if the death rate were large. As people die off, the number of potential new cases drops and hence ultimately, if unchecked there are no new cases.
The theoretical model of an epidemic is a normal-looking distribution that has a positive skew.
Look at Spain for example:
Compare that shape to the US, for example-----
In the US, we responded slower and I have heard a number of excuses, but it was basically that we were ill prepared and then acted slowly, indecisively, and clumsily. Which you can also see in the slower decline following the peak.
Or look at Italy, it has a shape similar to Spain.
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When you analyze deaths, there are other set of dynamics but the shape of the graph should be similar. See Death in Italy, compared to new cases.
You can see that the peak for new cases in Italy was around March 22 and the peak for deaths is around March 28. showing a typical time delay.
There are a number of things you can watch for, but if someone is interested in the question, “are we opening too fast?” then look at the shape of the drop in the case-creation rate. I am analyzing some data and I use the metric of “% reduction from peak value at 50 days". Spain is almost 90%, Italy is a little over 80% and the US is 30%. Hence the countermeasures in Spain and Italy, compared to the US have been, at least to date, more effective. They can open with a much lower risk of exacerbating deaths as they are creating fewer cases.
Ro
The Ro number, pronounced R naught. This is the probability of the infection rate. It is a complicated equation, logarithmic in nature and if <1, the epidemic is shrinking, if >1, the epidemic is growing. It is based on three factors, the infectious period, the contact rate and the mode of transmission. From these factors you can see why the aforementioned countermeasures are so important.
You can find a good article on Ro at
https://www.healthline.com/health/r-nought-reproduction-number
and there is a very good article at
https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article
I have extracted Figure 1 from this article….fyi
But the most important aspect for any country is to :
1-Be prepared with a plan.
2-When it is announced there is an outbreak immediately
a-begin testing to get data,
b-quarantine the infected,
c-track the history of the infected to find others that are exposed and quarantine them also
d-use masks so those who have been unknowingly infected, do not infect others
This protocol is not new and many countries used it. Look them up, they include South Korea, Hong Kong, Singapore and Taiwan…check their results. they all have per capital death rates that are orders of magnitude smaller than the US. They followed that protocol
The most important aspect is to act quickly. If you act slowly then get what we got here in the US, chaos and lots of deaths. I wrote an article on the exponential growth rate of an epidemic. It is available at
If you wish to discuss, correct (or have better data) please call, 915-203-4141, it is a much more effective means of dialogue than emails…
stay positive, test negative....