Is Omicron more Transmissible But less Severe Than Delta?

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1) Update: 15 December 2021: Detecting Omicron 
2) Update: 23 December 2021: Omicron, lesser hospitalization
3) Update: 29 December 2021: Omicron in GauTeng,  SA 

8 August 2018

The preliminary hospital data released by the South African (SA) Medical Research Council (SAMRC) appears to suggest that thus far.  This article intends to keep track of the development of Omicron.

What has been found?

This chart released by SAMRC gives us a glimpse of what we say about Omicron as far as transmissivity  & severeness are concerned.

The chart is showing us the following picture.  It tells us Omicron is about 20% more transmissible but  6 times less severe in terms of death at the present moment.

Updated Chart (To be updated regularly)

The attached is superimposing the new cases and death charts taken from Our-World-in-Data.  It is for the whole of  SA and it is also showing that Omicron is more transmissible but less severe than the other variants.  Until further notice, this chart will be updated regularly or when there are many changes. 

The following chart is the situation in SA & Botswana where Omicron is the predominant virus to date.  Omicron's new cases in SA have risen and are about to break their last record.  The death rate still remains muted.

What Can We Expect?

Many are of the view that these preliminary findings cannot represent the real power of Omicron because Omicron is a new variant.   It might mutate & further develop into a more fearful variant in the future.   There is also a time lag between the death and the infection figures.  In other words,  we might expect Omicron to have more deaths at later dates.

While this concern is likely,  the other variants are telling us the time lag between death and infection is usually about 10 to 20 days.  So far,  Omicron has been around for almost 9 weeks or 63 days.  We don't think there will be much change unless Omicron mutates further at a later date into a more vicious variant. 

What to expect for the 2-Dose Vaccinated?

Interestingly,  SAMRC also provided breakdown figures for the vaccinated and unvaccinated for Omicron infection.  

So far,  SA has a vaccination of about 30% which means 1/3 of the population is vaccinated whereas the other 2/3  is unvaccinated.   By using this vaccination ratio,  we could roughly estimate the effectiveness of the vaccines in SA to be about 50% as shown in the following workouts.

The 50% vaccine effectiveness is not enough to keep Omicron at bay.

Again,  the vaccine effectiveness is worked out based on the limited data.  It cannot represent the actual and real result;  however,  it does reflect that the SA vaccine,  which is predominately 2-dose Pfizer,  has lower vaccine effectiveness against Omicron.  These are also the findings of the most recent Pfizer laboratory work.  

What are the Pfizer Laboratory Findings?

Pfizer in its latest press announcement on December 08, 2021, has the following important claims

1)  The Pfizer's booster shot can induce antibodies that can neutralize Omicron to match the level comparable to other variants;

2)  The existing Pfizer 2-Dose may not be able to protect against Omicron.   It has been found to have a 25-fold reduction in the neutralization titers.

What is this 25-fold Reduction?

This is jargon in immunology.  It is a measurement used to indicate the fold-increase or reduction in the levels of neutralization of antibodies.   Here is a pictorial representation of how they work out the 25-fold increase/reduction.

There is a relationship between vaccine effectiveness and fold-reduction but at the present time,  there is no direct conversion available for working out the Covid vaccine effectiveness using the fold level reduction in antibodies.

What to Expect Now?

It has been found that Omicron is a heavily mutated variant.  It has been identified to have 30 changes to its spike protein whereas Delta has only 13 changes.    The scientists to date do not have many clues about how Omicron has acquired so many mutation changes and the speculation is that Omicron appears to be a much vicious variant compared to its predecessors.

The US expert,  Dr. Anthoney Fauci, pointed to the evidence about Omicron being more transmissible but less severe.  But he expected more evidence and data to come before he can reach a definitive conclusion.    Because Omicron is more transmissible,  it has been identified as a candidate "likely to mutate in places where vaccination is low and transmission is high,"    

However,  many experts including those in WHO are keeping track of Omicron closely as they are saying this Omicron could be a 'turning point" of the present pandemic because its behavior is much different from the rest of the variants.   This Professor of Epidemiology,  Prof Ralf Reintjes,  from Hamburg University was of the view that "Omicron could mark a positive turning point in this pandemic".  Let's watch what he was trying to tell us in this video.

Just to recap.  The experts are warning us that this Omicron is very transmissible but at the moment,   it is less severe than the rest of the variants.   However,  we are asked not to be premature optimism & expectation about Omicron.  

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Update: 15 December 2021

Detecting Omicron

The presence of Omicron can be detected using some brands of Antigen Rapid Test (ART) or LFT.  One can also detect Omicron by using PCR tests.  However,  ART or LFT can only tell if one is infected and it cannot tell by which type of virus.   Only the PCR test can tell the difference.    

In the past,  the laboratory will have to do genome sequencing to detect the difference.   This genome sequencing could cost as much as USD1000/= per sample because the detecting agent is quite expensive.   Fortunately,   Omicron shares a testing pattern quite similar to Alpha which has almost extinct and some manufacturers can come up with PCR testing kits that can detect Omicron fairly quickly.   So far,  the following brands have claimed that their PCR testing kits can detect the Omicron variants.

1.  Thermo Fisher Scientific, Abbott, Qiagen, Cue Health and Co-Diagnostics (US)

2.  Roche (Germany)

3.  Acumen (Singapore)

4.  IIT Delhi (India)

FDA said the following PCR test kit will return false-negative results.

Applied DNA Sciences, Meridian Bioscience, and Tide Laboratories 

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Update: 23 December 2021

South Africa is presently having the highest proportion (96%) of Omicron patients in the World.  Its National Institute for Communicable Diseases (NICD) has a daily surveillance report published on this website.    It has a network called "DATCOV-Gen" where studies about Covid hospitalization details are often reported.   One of its most recent studies published in  BMJ,  an internationally renowned medical journal, is shown here.  

The study report concluded that those suffering from Omicron are likely to have lower odds of being admitted to hospitals as compared to non-omicron patients.  The odds ratio (AOR) was estimated to be 0.2 @ 95% confidence interval (CI) 0.1-0.3).    In other words,  those suffering from Omicron would have an 80% lesser chance of being admitted to a hospital for treatment.

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Update: 29 December 2021

The infection rate in Gauteng,  SA has receded by 75% from 630 new cases per mil to about 120 cases per mil.   The hospitalisation rate came down by about 30% and death rates appear to be muted as shown in this chart worked out by Dr. Ridhwaan Suliman

Why this Global Energy Price Hike?

Jump to 

1) Update: 11 December 2021:US exports more LNG
2) Update: 17 December 2021: Asian LNG price jumped 21.1%
3) Update: 20 December 2021:US LNG Diverted to Europe
4) Update: 24 December 2021:China is Biggest LNG Importer

3 December 2021

There is always this rise in energy price during the winter months because the energy demand will be high especially when there is a colder winter expected.   In these months from November to March,  the energy price could fluctuate between 10% to about 50% in the past depending on how cold will be the weather and how long they will have to run the heating system during the winter months.  

But what happened this year?  Why our energy price has gone up so high,  some more than 500%?  This article will try to find out the answers.

What has happened?

This year,   the energy price has gone crazy.  Natural gas prices in  Asia went up by about 5 times or 500% compared to last year and the Crude oil price was also up by 60%.   The US's natural gas price is also not spared.  It went up by about 120%,  not as high as Asia and UK for some reasons.  But it lost about 100% in the last 3 months as shown in the following chart.  

double-click to enlarge the picture

The rise in crude oil price and natural gas price in the US could be caused partly by the prediction ahead of the extremely cold winter months.  It could be also partly influenced by higher gas prices in Europe and Asia.   But the European and Asian 500% jump in gas price has just gone crazy.  It is definitely due to other reasons besides the colder winter.  But what are these reasons?

Why so very high? 

   

There was speculation about the Russian was behind this crazy pricing.  There was also a strong view that the higher demand was caused by countries going for clean air,   converting all power generation to natural gas firing.   Another guess was about China turning to Russian gas for the supply of natural gas to supplement the power shortage happening in recent months.  There were reports that China had been shoring up natural gas supplies.

Russia Denied being the Cause

Russia was blamed to have contributed to the natural gas price in Europe.   They forced gas prices to go higher by declining to supply additional gas to Europe.  But Russia has denied this allegation.  Instead,  Russia blamed European nations for not doing their homework to increase their storage capacity.  

On the other hand,  the Western World is pointing out that China has stepped up its effort to buy natural gas at record level through the Russian pipelines in the North.   There were instructions

"asking its top National oil and gas companies in China to step up procurement, shifting its LNG purchase strategy away from volatile spot markets and boosting the supply of alternative generation fuels like coal in the winter months.".   The record-breaking buying saw China nearly doubled its gas imports from Russia from about 2.3 M mt of oil equivalent in July/August 2020 to 3.7 M mt in July/August 2021.  They import went up to This instruction came amidst China was facing severe power shortages,  causing frequent power supply cuts after having banned the imports of the Australian Coking coals earlier in the year.  China's natural gas consumption is about 370 Bcm in 2021. This consumption is almost equal to the consumption of the whole of Europe. 

As such,  the World,  especially the European countries,  must have been caught by the sudden increase in China's natural gas demand.   They might not have the time to increase their storage capacity to tie over the period.

Will the Natural Gas Crisis go away?

It is not a matter of when the natural gas crisis will go away but just a matter of when.  This is because "the world has proven reserves equivalent to 52.3 times its annual consumption. This means it still has about 52 years of gas left".

The Natural Gas crisis started by China and it will end by China.  China started increasing its import of natural gas from Russia in August 2020.  It has almost doubled its supply in a year.  This Russian article suggested that Russian is expected to supply 10 Bcm or 9.0 million mt to China in 2021. 

Because the Asian Natural Gas price is nearly 5 times that of the US,  there was an afford made by various Chinese conglomerates like CNOOC,  Sinopec &  other agents to buy LNG from the US at record-breaking levels.  This is despite the import ban of the US LNG after the trade war in 2019.    The test mode of bringing the US gas shall start end of 2021 and if successful,  the gas supply should flow by the first quarter of 2022.  

The following animated chart illustrates and expected the natural price hike to ease very soon if China can start importing natural gas from the US.

As for the very cold winter predicted earlier,  the authorities are now questioning the whereabouts as they have recorded mild weather patterns in November.  The World Metrological Organisation (WMO) has this forecasting model.  It worked out in November for many parts of the World including China and produced this chart.  The chart shows only the pacific ocean areas have some spots of surface air temperature lower than normal temperatures.  They predicted widespread warmer-than-average sea surfaces & air temperatures for December–February 2021-2022. 

In Conclusion

The spike in natural gas supply in Europe and Asia is likely to be caused by the sudden demand in China as they doubled their pumping volume recently.  This has made the price of natural gas gone sky high as China now turned to buy natural gas from the US.  We should see energy prices being tamed as soon as China has solved its energy problem hopefully by the first quarter of 2022. So far,  there are already report about Asian LNG price has fallen because China has muted its import.  This move has also caused Russia to increase its gas supply to European countries.

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Update:  11 December 2021

a)  US Export more LNG

The US Energy Information Administration (EIA) reported that the US's weekly LNG export increased by about 13% or 0.283 BCM (10 bn ft3) from 2.37 BCM (84 bn ft3) on 1 December to 2.69 BCM (9.5 bn ft3) on 8 December.     EIA said the US's LNG export rate would be increased by  20% from 2.69 BCM(9.5 bn ft3) by the end of Nov 2021 to 3.23 BCM(11.4bn ft3/d) by end of 2022.   It also expected the US's LNG export rate to increase by 72%  by 2024 to about 4.61 BCM/d(16.3bn ft3/d).  This 4.61  BCM/d  in 2024 will be more than enough to supply 70% of China's NG daily consumption which is around 6.34 BCM/d for 1.4 billion or 16 cubic feet per capita per day.   It is likely also that the EIA's expectation to increase LNG export by 20% in 2022 might help to solve the supply problem now happening in Europe and Asia.

b)  Putin ordered to increase NG Supply to Europe

Russian President Putin on 7 December ordered Government to work out a proposal by March 1 2021 to supply 10 BCM of NG to Europe.  This amount is equivalent to about 5 weeks' of LNG export of the US.    

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Update:  17 December 2021

Asian LNG price rises due to supply concerns in Europe.  The Asian LNG price for February rose to $43.35 per metric million British thermal units (mmBtu), up 21.1% from $35,8 from the previous week.

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Update:  20 December 2021

Although the Chinese were buying the US LNG,  it is unlikely to see the LNG price in the Asian region easing soon.  This is because they are re-shipping & diverting the US LNG shipment from Asia to Europe for better selling prices.

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China Surpassed Japan as World’s Biggest LNG Importer Through October.  China became the world’s largest liquefied natural gas (LNG) importer during the first 10 months of 2021, according to data from government agencies. 

Choosing the Right Extension Cord and Wirings

Many a time,  we use an extension cord to extend our power supply for connection to a laptop,  Hifi Audio,  Television, and many other appliances.  They are cheap & easily available.  Sometimes,  we use such extension cords for slightly heavy current appliances such as electric irons & kettles.   

Most extension cords we buy off the shelves are not suitable for very heavy current appliances,  not because the plugs and sockets cannot take the load but because the flexible cable used is too small for carrying such higher electric currents.  A quick test one could do is to turn on the appliance for about a minute,  we should feel that these underrated cables will start to warm up.   The better extension cord will always have the ratings specified on the extension cord but the cheaper ones might not. 

This article will try to give some information on how to choose the extension cords and how to size up the flexible cable if one decides to DIY an extension cord.

Extension Cords

There are generally 3 types.  The common ones are sold as switch socket outlets.   They are either in single,  double, or multiple gangs as shown in the top left-hand picture. The other common ones in cable reels where the cables can be reel in and out for storage purposes as shown in the top-right-hand picture.  For those requiring heavy-duty for industrial applications,  they are shown in the lower pictures. 

What to look for?

When buying an extension cord,  it is important to know what we will be using the extension cord for and how long will be the cable or rather how far the appliance will be located away from the wall power sockets. We will be looking at the load-carrying capacity of the extension cord and the loading distance of the extension cord.

a)  Load-Carrying Capacity

For example,  if we are using the extension cord for television,  HiFi audio set,  laptop, or Christmas lights, most extension cords will be able to do the job.   But if we use the cord for electric irons and kettles which will drain higher current,  we will need to be careful and pay some attention to selecting the correct type of extension cord;  otherwise,   the cable might not be big enough to "carry" the electric current or the load.  As a result,  the cable might be heated up over long hours of operation. The wiring insulation could melt causing electrical short-circuiting,  giving rise to fire incidents.

The better ones and branded ones will usually have a rating specified on the extension cords.  Most of them will have a rating capable to handle a maximum load of 13 A or 3,000 watts.  That would mean it could be used for an electric iron or a kettle which usually consumes about 4 to 5 amperes or 1,000 watts.

b)  Loading Distance

The household extension cords usually come in fixed-length of around 2, 3, or 5 meters;  some, 3 meters long;  extension cords the heavy-duty or the industrial type can be of lengths 20 meters or more.  Users do not usually have to worry about the cable ratings of extension cords so long as one is using the extension cords within the manufacturer's maximum specification.

Extension Cord Ratings & Safety Labels

Various countries have different statutory requirements or safety codes for the use and application of extension cords.   Most regulatory authorities will want the extension cords to comply with the local manufacturing safety standards.  Nonetheless, it is always wise for users to choose a brand that has a safety label sticker over those which neither give any ratings or brands or operating ratings.

What about DIY?

DIY is not any cheaper than those available off the shelves but if one needs a specific length of cable,   the only way is to design and self construct the extension cord.

What to look for?

The things to look at are about the same as the commercial extension cord except one will have to size up the cable.   One would need to size up the cable to handle not only the carrying load but also to account for the voltage drop caused by the cable.  

Take, for example,  a cable of a certain size that might work fine when the cable is short but might not even be enough to run the same appliance when the chosen cable is about 30 meters long. This is because the voltage at the receiving end might have dropped to below the acceptable limit for the proper running of the appliance.

How to size up the cable?

There are 3 common and different sizes of flexible cable one can easily buy off the shelves;  these are specified in the following manner under the imperial system:   23/0076 & 40/0076 & 70/0076 as follows.

The Technical specification of the flexible cable under the imperial system is as shown in the following.  There is also one for the metric system.

  

Column 3 of the table indicates the maximum ampere that the cable can carry and volume 4 and 5 indicates that voltage drops for the cable to carry the maximum ampere. For household application which is usually 1 phase ,  we will be looking at column 4 to size up the cable. 

Let's assume we have an electric iron consuming about 1 kW @ 220 Volts,   that is roughly 1000/220 or 4.5 amperes. The above table says 23/0076 can take up to 6 amperes which might be able to carry the load.  But in turn of voltage drop,  it will have 4.5/6*11 or 8.25 volts over 100 ft or 30 meters,  this is about 8.25/220 or 3.75% which is higher than 2.5% specified under the regulation, Therefore,  this cable is not suitable under such usage.

The next cable size (40/0076) will have 4.5/13*14/220 or 2.2% voltage drop.  It might just make it but the one size larger (70/0076) would be more suitable for prolonged hours of usage.

Testing

It is always good to ensure that the correct size of the cable has been selected for the operation by also measuring the temperature of the cable when it is under operation.   The cable temperature should not exceed 70^oC.   One should also ensure the cable is always installed according to the acceptable color code which is green/yellow for earth, blue for neutral, and brown color for the line or live cable.  

Replacing 2x40 Watts Fluorescent Fitting with LED Downlights

We have a situation where 2 Nos of 40W 4 feet fluorescent fitting were fitted inside a lightbox having an egg crate lighting diffuser at a ceiling height of about 3.5 meters.   We wanted to change them into LED lightings not only to save energy but also to get a brighter lighting system for the sitting room.   We came across these cheap 5 watts downlights which we have retrofitted with good results.  This article will describe how we retrofitted them and how we improved the lighting system with cheap materials found in the house.

The Downlights

These downlights are not only cheap, but they are also quite bright if one only could carefully read the reviews that some of the buyers were saying.  We replaced the 2 Nos of 40Watts fluorescent fitting with 8 Nos of these little glitters and managed to get a better and brighter lighting level.

How?

As advertised & to our surprise,  we found the brightness of this little glitter is equivalent to about a 60-80W incandescent lightbulb.  As downlights are direct lightings, their lighting output will not be cut by the egg crate diffusers which we had had in our old lighting setup using 2x40 Watts fluorescent fittings. 

Retrofitting

The retrofitting was relatively easier with the egg crate diffuser.  All one needs is a wire cutter that one can use to cut a hole of about 60 cm in diameter. Wiring up was a piece of cake with the quick wiring connector that one can wire up the lamps in a matter of half an hour with simple double core wirings.  Each lamp consumes only about 5 Watts so any type of double core wiring would be suitable.

Calculated Energy Saving

If what was claimed is to be true that each LED downlight consumes only 5 Watts,  the total wattage saved for replacing the 2x40Watts fluorescent fitting will be around 60 Watts considering that a 40 Watts fluorescent fitting will consume 50 watts including the ballast which will consume another 10 watts.   The total saving would be roughly  60 W x365 days x5 hrs per day or about 109 kWh per year.  At an electricity cost of around $0.25 per kWh,  the saving  would be around $27/= per year.  This is about twice the cost of the downlights which is around $1.60 each.

Shortcomings

The only shortcoming we have had is the glare from these fittings.  It is quite unbearable especially when it is installed at such a height.  It is quite eye-catching and disturbing when one sits on the couch,  looking at them.  There were no lampshades we could find online to fit the lamp.  Finally,  we use cupcake plastic bowls we found sitting at the corner of the house.  This is how we did it

Things to watch out

1)  Buying the downlights

There are many varieties of downlights available online. Most of the cheaper ones are from China. They all use the same advertising pictures and descriptions and appeared to be the same but actually,  they are from different manufacturers;  therefore,  they can be entirely different.    When they claimed to be white light in color,  some might be a mixture of bluish and yellowish light.  The lighting level can also differ.  It is good to read the review to buy the correct type.

2)  Cutting the holes in Egg Crate Diffuser

The plastic could be old and brittle after some years of working.   Be careful when cutting the hole.   Plan first before deciding where to cut the hole.  It would not be possible to repair the hole after the hole cutting.   Hot glue is good assistance if some piece of the egg craft came loose while cutting the hole.    It is a good practice to glue a round plastic ring to reinforce the rims of the egg crate cuttings.

3)  Safety First

Go without saying.  Make sure the power is always off before doing any electrical work and advise that no one will turn on the power while one is working on any electrical wiring work.

 

Austria is Locking Down Again

Austria announced last Friday that they are locking down.  This is the fourth national lockdown.   The lockdown will begin on 24 November;  it is likely to last for the next 10 to 20 days. 

This lockdown shall make  Austria the second European country, after Latvia, to impose lockdown measures since vaccines became widely available earlier this year.  Further,  Austria is contemplating making vaccination compulsory.  

What's the use of Lockdown?

Lockdown is an effective but primitive way to curb the spreading of all types of diseases. Lockdown has been used for centuries whenever there is an epidemic.  The idea is to isolate the patients especially those asymptomatic ones so that they won't have a chance to roam around, spreading the diseases to other healthy people in the Community.  This article will show that asymptomatic patients are responsible for more than 60% of the Covid transmission.    

Lockdown is good,  but it comes with a price.  Many people especially those in Western Countries so hated lockdown that they often went to the streets protesting against such practices.   

Mass testing will also have the same effect of "isolating" those asymptomatic after "flushing" them out from the community.   ART is a good alternative to mass PCR testings.   Proper use and handling of ART is not only cheaper but also more cost-effective. 

The Situation Right Now in Austria

It is not looking good.   The infection cases shot up about 3 times from 586 per million on Oct 12 to about 1562 per million on Nov 22 for slightly more than 40 days.  It is sad to see that the death rate has also doubled in that period.  However, it was not as serious as before and after 2/3 of the residents have been vaccinated.

What could have happened?

A new Covid wave has been formed except this time,  Austria is better prepared as shown by the following charts.

The charts show clearly that Austria has done plenty of testing.  The rate is around 77 tests per 1000 people. This rate is about 4 times more than the UK's 13.5 and 15 times more than Singapore's 3.2.  However,  the positive rate of the test is not high @ 2.8%.   The exceptional high testing rate in Austria explains why its infection rate has gone up so fast and so sharp.   The charts also show that Singapore's positive rate is exceptionally high @ about 17% which is about 4 times that of the UK's  4.6%. 

Why Singapore has such a high Positive Rate?

Normally,  any Epedilogist will say countries having a high Positive Rate is not a good thing.  It means the infection is very serious;  there must be a lot more other infection cases still roaming in the streets.  The infection wave is not over.   More new cases are expected.   However,  this is not the case in Singapore.   Singapore has just seen its new cases drop by 2/3 over one month. This is as shown in the following chart which is plotted in the daily-infection interval.   The new cases dropped from 976 per million on 27 October to 326 per million on 23 November.   

Why so?

It has something to do with the mandatory Antigen Rapid Testing (ART) that Singapore has just implemented in September 2021,  and the detail of which is explained here.  Singapore managed to find 5 times more or about 3,000 to 4,000 asymptomatic patients per day using ART and isolate them quickly to prevent them from spreading Covid in the community.  

As the Singapore Authority is replacing the screening PCR testings,  they cut down the PCR testing frequency,  resulting in higher positive rates as illustrated in this chart

In Singapore's case,  the higher positive rates are not caused by the seriousness of the infection.   

Of late,  the experts in Singapore are questioning the needs of the electronic system that traces Singaporeans' outdoor movement for reasons to track the contacts of infectious patients.   

How Austria can Get such a high Testing rate but a low positive rate?

This might have something to do with the free and uniquely PCR Self-Test method introduced by Austria in September 2021.

https://www.afr.com/policy/health-and-education/why-citizens-in-pandemic-vienna-keep-gargling-20210922-p58tzr

In such an exercise,  everyone in Vienna will be given a PCR test (gargle box) free.  They can pick up the box at any of the 22 BIPA outlets.  After doing the test,  the box is handed over to the REWE outlets or the petrol stations.  Users can get the test result within 24 hours. 

The exercise could have gathered lots of  PCR testing samples.  Because 2 tests are required to confirm infection cases and they have to go through each and every one of those samples,  the positive rate would naturally be lower.

Because of the very high testing rate and high infection cases which primarily are assumed to be asymptomatic patients,  Austria should see the crisis over in a very short time.

Can Other Countries do the same as Singapore?

There should not be any reason why other countries cannot do and repeat the same;  after all, the ART testing method started in Europe and the US.   All they have to do is to make ART testing kits easily accessible to residents.   People are curious by nature and afraid to die.  They will want to know what's wrong with them.  They will use the testing kits one way or another.

As for Singapore,  it should not rest on its laurels.   It should continue to make improvements,  making ART test kits freely available and accessible to all Singaporeans,  residents, and even the short-term travelers at no or little cost over 24/7 outlets using ATM machines located all over the island.  After all,  asymptomatic are the ones that contributed most of the infection cases because of the sheer numbers.  The government could save the cost through savings in the reduced numbers of PCR testings.

 

Estimating the Transmission Risk of Asymptomatic in a Community

It is generally known that symptomatic patient has a higher transmission risk.  According to this article by Yale Medicine,  a Delta symptomatic patient can spread to maybe 3.5 or 4 other people.  As for asymptomatic patients,  the common knowledge is that its transmission risk is relatively low. This article will try to examine from a different approach why some were saying that asymptomatic or people without symptoms are responsible for about 59% of the Covid transmission.

What happens at the site?

Ministry of Health (MOH) of Singapore has this pie chart showing that about 98.7% of the patients are asymptomatic or patients with mild symptoms.   This has been the case for many months.  It is quite clear that there are lots of asymptomatic/patients with mild symptoms in the community.  

How are they Responsible for the Transmission?

One can always argue that asymptomatic is not responsible for the spreading of Covid in the community.    It is always the symptomatic patients passing on the Covid to the asymptomatic.

According to this study which examined and traced the contact histories of about 7,000 people,  asymptomatic patients have a transmission rate of 0.06% whereas symptomatic patients have a rate of 1.12%

In other words,  let's say we have 10,000 people in a community,  9,800 people are asymptomatic and 200 people are symptomatic or pre-symptomatic as found out according to the MOH Singapore,  we might have this situation:   

Therefore,  there is a possibility that the asymptomatic can be 75%  responsible for the spreading of Covid in the community.

Other Studies

There are also other studies that have similar findings;  for example,  this study from Oxford Academy found that the secondary attack rates of symptomatic and asymptomatic were 4.1% (128 of 3136) and 1.1% (12 of 1078), respectively.  This Oxford study indicates that asymptomatic can have an even higher transmission risk,  causing or contributing more infections in the community. 

Conclusion

This simple example confirms this article saying that asymptomatic or people without symptoms are responsible for about 59% of the Covid transmission.  Therefore,  we mustn't underestimate the importance of asymptomatic patients who are usually hiding in the community.   These patients will always stay and spread Covid in the community until there is a mass-testing done to flush them out.  In the case of Singapore,   instead of using mass testings,  they introduced in September 2021 the mandatory Antigen Rapid Testings (ART) for the workers and residents.  This has helped to flush out about 4 to 5 times the number of these asymptomatic patients hiding in the community.