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Saturday, November 13, 2021

Infection Rate vs Case Fatality Rate

Everyone is afraid to die.   In Covid Epidemiology,  Death is often measured by death rate,  i.e number of confirmed death per million or 100,000 people.   It is also measured by Case Fatality Rate (CFR).  CFR is the percentage ratio of the confirmed deaths over the confirmed infections.  

CFR tells also the seriousness or the severity of the Pandemic.   A higher CFR means more people are dying after catching Covid.  
However,  it is not always true;  a country having a very high infection rate and a very high death rate can also have a very low CFR.  

To accurately assess and interpret the seriousness and severity of the Pandemic,  one should also examine the infection and death rate together.

This table gives some ideas on what to look for:

Death Rate
CFR
Infection Rate
HighLow
High
HIghVery High RiskHigher severity and risk; Could be many infected not being counted
LowHigh severity and risk; could be caused by high Infections & high deathsNA
Low
HighNAMight be many infected or dead not being counted
LowLow or lesser severity and risk if the majority of infected are asymptomatic or false positiveVery low severity and risk

A high infection rate with a low death rate and a lower CFR could mean there is a lot of asymptomatic patients,  a condition likely to succeed in progressing towards the endemic condition.    A situation with a low infection rate,  a low death rate, and a low CFR is ideal but the residents must always be alert,  well prepared and well trained,  ready to face any Covid attack from the external communities or countries.

Navigation:
1.  3 top buttons are for adding and selecting countries.  The right button is for adding countries to pre-selected countries.   It will be displayed when the region and type buttons are selected.  The middle button is for selecting & building up countries(not working); the left button is to select chat lining in parallel or top/bottom at full width; 
2.  Use dropdown boxes provided to select the menu for charts;
3.  Use <ctl><click> to select on country or <shift><click> to select several countries in <select countries>;
4.  Use [Call/Save Chart] to call and save the existing chart.  The data saved can be erased by browser memory clearances;
5.  Use the [Expand] button to expand/contract and examine each chart.
6.  To go to Our-World-in-Data page,  just click the "full screen" symbols.  It is located at the bottom right of every chart.

  


The Use of CFR

One can use CFR often to assess if a sudden surge in the Infection rate is caused by a new wave or by some changes in the measures that control the spread and the transmission of the Covid.  

For example,  there was a spike recently happening in Singapore.  The infection rate shot up 6 times in a short span of time,  from about 800 cases per day in mid-September to about 5,000 on 29 October. 

Many blamed the effectiveness of the vaccines.

This chart will easily show that the spike has not much to do with the effectiveness of vaccines or the Health Services.

The chart shows the Covid situation in Japan,  Germany, and Malaysia.  Malaysia has just tamed the Covid with infection and death rates lower than Singapore at the moment.  One can explain that Malaysian's higher CFR might be more due to the slightly better Health Services in Singapore.  But it would be difficult to explain why the Japanese and German CFR are also higher than Singapore,  except Singapore has just implemented mandatory Antigen Rapid Testing (ART) from September 2021.    This mandatory ART testing has helped to flush out a lot of asymptomatic in the Community. 

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