How To Estimate the Efficacy of The Vaccine

18 May 2021

(Updated 14 June 2021:  Added UK Data)

 

If you receive this piece of news, what would you think?

The news is about Seychelles,  a small island country somewhere in Indian Ocean. The paper said this small nation has 37% of the infected people fully vaccinated.

 

https://www.reuters.com/business/healthcare-pharmaceuticals/who-reviewing-seychelles-covid-19-data-after-fully-vaccinated-people-test-2021-05-11/

To some,  this is really a shocking piece of news.  To others,  they might "brush it off" claiming it is just another fake news.  Unless the vaccine is useless, it is hard to believe. How come one can get infected so easily when one already has the  full 2 doses of vaccine. 

 

Now, what exactly does that News report really mean?

Vaccine Efficacy 

“Vaccine efficacy” is a familiar term nowadays.  It simply tell how effective is a vaccine in reducing the virus infection.   If we say Seychelles' vaccines have a combined efficacy of 60%,  one will quickly understand that the vaccines are actually working.  Just that the vaccines are not having very high efficacy.  It is as claimed by some countries. We have also an infectious African variant,  B1351,  "roaming" around.  This efficacy is still above the threshold of 50% set by WHO for approval under emergency usage.  The question now is how to roughly work out this 60% efficacy without all those laboratory tests and trials ?

 

Efficacy Measurement

The vaccine efficacy is always worked out by carrying out the tests in a laboratory or otherwise under controlled environment. This is to ensure the variables that will affect accuracy are kept to a minimum. In the real World, it is unlikely to accurately measure the efficacy vaccine.  This is because one will know how many people have been infect and there is no way to tell how many were exposed to the virus. But there is nothing to stop us from estimating the "Vaccine Efficacy" or usually termed as "Vaccine Effectiveness" for the purpose of knowing if the vaccines we have taken are in order.  

 

How to Estimate the Effectiveness?

Take the case in Seychelles for example, in the news report, we can gather the following information:-

1.  37% of those infected people were fully dosed 

2.  The seven day rolling average of positive cases increased from 120 on April 30 to 314 on May 8

3.  Nearly 60% of the population have had two doses. (about 66% in other news report) 

From some other websites, we can also find the following information

1. The total population of Seychelles is 97,625

2. This Reuters news report is on 12 May 2021

We can also gather these information from this page or alternatively,  from graphics.reuters.com & www.worldometers.info.

1. The total number of infection between Jan 12 and May 11 2021 is 7,571;

2. Seychelles’ vaccine roll out date is 12 Jan 2021

Equipped with these information, we can now roughly work out the attack rates of those vaccinated (ARV) and unvaccinated (ARU) .  

Finally, using the standard Efficacy rate of the Vaccine formula, we can work out the rough effectiveness for the vaccines used in Seychelles.  This is roughly 60.70% as shown in this example sheet

 

Similarly,  we can also work out the vaccine effectiveness roughly for other countries and a copy of which is shown in this table

Interactive Template

One can use the follow template to estimate the rough effectiveness in your country if you also have the required information 

(Note:  Please doubleclick the following image to be re-directed to the calculation template or Just click this link )

UK Example  Updated (11 Jun 2021) 

UK Public Health released a report on the effect of Covid-19 Variants.  It has this table 6 on page 15 reported about infection &  deaths of Delta (Indian Variant) confirmed cases from 1 February 2021 to 7 June 2021. 

The report said 9,344 vaccinated people were infected,  among them 1,785 has full 2-doses.    Using this information,  we could roughly estimated the UK's vaccine efficacy to be about 74% for all vaccinated,  93% for those having full doses only & 68% if we were to include only the vaccinated & unvaccinated. 

Note: This is the efficacy estimate only against Delta variants

About the Method

This is a simple example.  The aim is to give users a reference to  work out roughly and compare the combined vaccine effectiveness.   The example uses the "window" between rollout date and the breakthrough date.   Users can always choose other "windows" if the information are available. 

In the  real World,  there is always a difficulty getting the numbers for the people exposing to the disease,  especially for those unvaccinated. This information are required to work out the attack rates. 

It is a common knowledge that in the real World,  the vaccinated and unvaccinated are not living & working together . Their risk of exposure to the virus are much different.  Any attempt to estimate the vaccine efficacy over a short period &  over a sudden spike can be misleading.

Take the case that happened in Singapore in recent weeks. 78 people with full doses among some 400 others were found infected. Attempt to use these information to work out the vaccine efficacy will yield misleading result. This is because most of the 78 vaccinated were front-line staff.  Their exposure to virus will be much higher than those unvaccinated whom they were serving.

 https://tinyurl.com/u2ts2hfn

Coronavirus Vaccine Tracker (Nos of Countries using Vaccine)

17 May 2021

 

Various countries have approved 15 vaccines so far for emergency use. About 60 of other brands are still in various development stage. Out of the 15 vaccines approved for use,  WHO, The World Health Organization has only approved 6 of them. This is as shown in the following table. 

 

Vaccine Approvals 

It is not mandatory for country to use vaccines approved by WHO. Individual country has own list and approval guidelines. 

The number of countries that have approved the use of various brands of vaccine are shown in this 3D Pie Chart. 

 

>

https://www.raps.org/news-and-articles/news-articles/2020/3/covid-19-vaccine-tracker

This 3D Pie chart shows that the 4 US vaccine manufacturers  have the approval from most countries.  One of the reason for the bigger share must be because their vaccines have better efficacy.

 

Market Rumours

There are lots of rumours in the market about which vaccine is better. Some rumours claimed that the Chinese or Indian vaccines are the best. They said the mRNA vaccines offered by Pfizer and Moderna are not the traditional type. Hence, not quite safe. There are also claims that mRNA vaccines have more severe side effects.

Some even claimed Sinovac and Sinopharm have better protection against death and hospitalization. This is despite they have lower efficacy.  

 

As most claims did not have data to back them up.   Also there is no World standard for the measurement, this article will not discuss them.  

 

Presently, there is only one acceptable measurement. That is the the measurement of efficacy for the vaccine.

What Exactly is Efficacy?

Efficacy is a measurement that tells how well the vaccine can reduce a disease infection.  It is worked out by comparing the infection rate or attack rate of some 30,000 recipients.  These recipients are divided into 2 groups,  one vaccinated and the other unvaccinated.  They worked  and lived in a community under a controlled environment.  Their conditions were monitored and their blood samples taken regularly to measure the virus attacks.   

There are also 2 other terms that are often mentioned. These 2 terms are effectiveness & efficiency of the vaccine. Presently, there is no such acceptable measurement standards available.

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The Efficacy of Various Brands of Vaccine

The Economist has a very good chart showing the efficacy of various brands.     This chart shows that Sinovac's efficacy is too close to WHO's 50% threshold for listing of vaccines for emergency use.

https://www.economist.com/graphic-detail/2021/04/15/in-clinical-and-real-world-trials-chinas-sinovac-underperforms#

Find out which Country use what vaccine most

The Our-World-in-Data has this chart that one can check what countries use what type of vaccine and how much of it.  The chart is reproduced here

Translate the chart into numbers,  one will get the following tables

Should One Wait for Better Vaccine?

Every country is now chasing after available vaccines.  As a result,  vaccine is in very short supply. The advice generally is to take whatever vaccine available. This is because the vaccine of choice might never come.

There were fierce debates among Scientists whether one can switch to other brands. There were no decision as there was not enough data to back up the claim.  Nonetheless,  some recipients in some countries took different brands by mistakes.  There were no adverse reports lodged. It would appear likely that switching to other brands might be a possibility.

https://tinyurl.com/3uwpn5wa

How To Embed Twitter Videos in BB Forums & Blogs

16 May 2021

How To Embed Twitter Videos in BB Forums & Blogs

Twitter allows embedding of its videos in various kinds internet medias and discussion. But, it is not easy to have them embedded in a BB Forums. This is because most BB Forums accept only iframe codes. This article will offer a method where users can get twitter video embedded in such forums

What you need?

This iframe code

<iframe src="https://twitframe.com/show?url= https://twitter.com/i/status/1289954190756782080" style="border:0px #ffffff none;" name="myiFrame" scrolling="no" frameborder="1" marginheight="0px" marginwidth="0px" height="850px" width="600px" allowfullscreen></iframe>

This code will work as long as https://twitframe.com/ is not down.

How to Embed?

Just right click any twitter video and copy the video address. Then paste it to replace the url address shown in the above example.  After that,  just simply copy the whole iframe code and paste it to the BB Forums or put the iframe code as a script in the HTML page of the blog.

Is this Legal?

It is perfectly legal as twitter does allow copying of the video for embedding in webpages. The iframe code is just an alternative mean of embedding the video

Water & Electricity Saver for Instantaneous Heater

Important Note & disclamers :  Modification to any water heater is extremely dangerous.  It should only be done if only you are familiar with the device as there are many accidents involving electricity electrocutions if the modification is not done properly.  

The alternative and safe way to achieve the same result is to turn on the tap to switch on the instantaneous heater on a high setting for a few seconds  and then turn off the tap for the water in the heater to be warmed up.

This article is just for reference only.  The author assumes no responsibility whatsoever.

Introduction

In tropical countries,  electrical instantaneous heaters are often used.  This is because residents often need only heating for showers. These heaters do not occupy space. They often save water and electricity as compare to water storage heaters. Also, they are less than 3 KW and can be powered from the usual 13 Ampere power point. This article will describe a device that will further save some water and electricity.

Working Principle

Every Instant water heater has a small heating exchanger. It gets power through a set of micro-switches that select 2 or more heating elements to warm up the water. The modern ones nowadays use electronic TRIACs to control the heater.

 

For these heaters to heat up the water, one needs to first set the selector switch and turn on the water. The water pressure sensor will pick up the pressure and actuate the micro-switches. These switches will turn on the appropriate heater element to heat up the water in the exchanger. The schematic circuit diagram of Aerogas Elegance water heater is as shown below:

 

Water & Electricity Savings

To heat up the water, water must first flow through the heater for the pressure sensors to pick up the pressure. Water amounting to 1.2 litres will be wasted before warm water can flow out of shower head. At the same time, electricity amounting to about 8 Watts-hr will also be wasted. Assuming a household of 4 persons might take 6 showers per day,  a total of about 2,600 litres of water and 17 kWh of electricity can be saved per year. This might sound to be petty savings for one household.  But it is still a sizable saving for a township of more than 10,000 families.

 

How Water and Electricity Can be saved?

To save, one can use this electronic gadget called “Trigger Delay Time Off Timer” as shown in the following:

 

Circuit Description

The gadget operates on 220V AC supply.  The delay time off is triggered started by a button.  The complete schematic diagram is as shown below

For the gadget to work in the seconds range, the default variable resistor must be changed from 50K ohm to 5K ohm. As the heater will consume 9-13 amperes, it is also necessary to add an external relay. The built-in relay has only a 10 ampere rating.

This gadget has an opto-coupler to isolate the trigger button from the 240V Supply. But the button is linked to the neutral terminal of the 240V supply. It does not offer complete electrical isolation. It will be ideal if there is an isolating transformer for electrical isolation.

 Wiring up

Safety Precautions

Important Note: Wiring up will need one to know about safe use of electricity. A wrong wiring such as wrong polarity connection by interchanging the line and neutral wires for example,  can cause shower head or water to be alive. It can be dangerous causing electrical shorts and execution.

Whenever possible, use only push button of plastic material. If metal material is used, its body must be connected to the earth.  Only waterproof push button can be used.

Further, one should always test the integrity of the heater’s earthing system. The method described in this article can be used to test theearthing.

To further protect the heater, it is recommended to install the following:

1) A Thermal fuse to cut the supply to the relay when the heat exchanger reaches an abnormal temperature of 85^oC. This temperature is about twice the normal operating temperature of the heat exchange. The thermal fuse must be of non-metallic type.  It is to be attached to the heat exchanger for proper operation.

2) A surge diode is to protect the relay contacts from electrical arc welding. This will prevent the relay from welding. Heat exchanger is wire wound. They cause inductive current that could cause the relay to use and weld together. The surge diode will clamp the voltage to less than 328 Volts. This is the breakdown voltage of the 400V surge diode.

For information, the thermal fuse and the surge diode would cost less than USD$1/= each. It is good investment for a piece of mind.