Coronavirus: Is it slowing down?
How can the numbers help us understand the virus spread? Are containment measures working?
Coronavirus, named Covid-19 has become enemy №.1 for the whole world. It is time for us to act together and put an end to it.
As of 13th March, there are
- 110+ countries affected
- 130,000+ cases
- Close to 5000 deaths
How can the numbers help us understand the virus spread? Do we see exponential growth? Or is it logistic growth?
Data, Data and Data
If we look at the cumulative count of patients, it paints a terrifying picture with no end in sight. It looked like it was slowing down around Feb 23. But unfortunately, it started spreading in other countries around that time.
Every country acts differently in response to the virus. Every country vary in terms of
- Government response
- Weather and other factors
- Behaviour of people
Overall if each country puts an end to the virus, we can defeat it. This makes it essential to understand the cumulative count of patients country wise.
Let us take the case of South Korea. Initially, it appeared like an exponential growth till Feb end. Also, at the same time, the government led a massive crackdown to fight against the virus. This seems to have slowed down the growth rate.
Now it appears more to be a logistic growth.
What is logistic growth?
Let us say you started a rumour in your office group about your boss. You tell your friend, your friend tells two more people. These two people tell four people. The rumour spreads exponentially, but eventually, it is going to level off (Because there are no more people who haven’t heard the rumour).
This growth of rumour is logistic growth (even though it started exponentially).
The same happens for the population in a few countries. Initially, it starts exponentially, but as resources reduce — it levels off.
- South Korea Population curve somewhat seems to be like levelling off after growth in the 1970s.
Here is an image from Khan Academy to make it simpler to understand
To draw reference,
- Per capita growth = Growth of virus
- How to make it a logistic curve? — By containment and other measures as suggested by WHO and other countries.
For mathematical reference, one can refer to this article
Coming back to the spread of coronavirus, we can also see that China’s effort in controlling the virus has lead to logistic growth. Now the virus seems to be levelling off in China.
How to tell when it is changing from exponential to logistic?
We all need to be looking for something known as the inflexion point.
- The daily growth starts to slow down
- If there were 500 cases yesterday, and today there are 450 cases, and tomorrow there are 420 cases — it is a sign that all the measures taken by the country are being successful.
As we can see in the case of Italy (as of 13th March), it still appears exponential. The drastic containment measures should help Italy attain logistic growth.
Conclusion
What is the scenario in every country? We can categorise them as
- Nascent Stage (Countries with less than 1000 affected)
- Most affected countries (Countries with more than 1000 affected)
Most affected countries can be further categorised as
- Exponential Growth Stage (Doubling cases less than a week)
- Slowing Down (Attaining logistic growth)
Currently, out of the most affected countries, it is slowing down in China and Korea (Data as of 13th March)
- China: We can say it has attained logistic growth and levelling off
- Korea: The virus appears to be achieving logistic growth and may level off.
In the rest of the most affected countries (Iran, Spain, France, Germany, USA), it is still at the exponential growth stage. In Italy, we see the drastic containment measures by the Government. The extreme containment measures should help Italy attain logistic growth.
Each country should probably follow suit, learn from the pros and cons of containment measures from Italy and attain a logistic growth. Probably take drastic measures if they still see exponential growth.
Will keep you posted as and when there’s more data.
