Dr. JB Lim On Tests For Covid-19

Note: The blogger is given the privilege by the Great Sifu Dr. Lim Ju Boo to post inside this blog his responses to Tan Sri Prof. Gupta’s questions on the recommended test and treatment of Coronavirus that is current raging the world.

WhatsApp Tue. Apri 7, 09:00 PM:

Dear Prof Dr Lim Ju Boo,

Can you advise us which is the best test to do for Covid-19 and what treatment can we use to protect ourselves for this terrible pandemic infection?

You are the only person whom we trust and greatly respect with your vast, vast knowledge in everything!

Thank you.

Gupta

Email Wed, Apr 8, 11:36 PM from Dr. JB Lim:

Dear Prof Tan Sri Gupta,

Thank you for your two very difficult and challenging questions to floor me down.

First of all I do now know many things, and I am unsure how to answer your requests

I can only try my level best.

Pertaining to your first question which is the best test to use for detecting corona virus infection depends on what we are looking for.

1. Are we looking for the presence of the virus, meaning the specific protein called the surface antigen found on the coat of the virus and subsequently in the throat of a person of an infected person, but has not developed the disease or the symptoms yet?

Or,

2. Are we looking for the antibodies produced by the person already infected and has the disease?

For both 1 & 2 above, it depends on what we call “specificity” and “sensitivity” which is again subject to the method used, such as using the (rapid) diagnostic kits.

Some tests are very specific for that antigen (protein) expressed, example by this SPECIFIC and particular corona virus (covid-19).

Then we have to look at how sensitive a particular test we are going to use.

For instance, if a person has just a small amount of the virus stuck in his throat, or if the examiner did not do a throughout swab on his or her throat, then he is going to pick up very minute quantities of this antigen (corona virus).

Hence we can confidently say even if a particular antigen test is very specific, yet it is NOT sensitive enough to detect such a minute amount of the virus on his throat.

In short, it depends on the methodology, how the examiner takes the throat swab and how much virus load there is in his throat or even down his airways.

Almost all of these tests are plate-based assay called “enzyme-linked immunosorbent assay” or ELISA which I mentioned many times before in this chat group.

This antigen detection test depends on a colour change on the wells of the plates, and this takes only a few seconds to read. That is why this test is called rapid test using commercially-prepared kits.

However I need to warn everyone if the test results come out negative because it is neither specific nor sensitive, you can give a person tested a sense of false security.

The best and most reliable test is by using the reverse transcription polymerase chain reaction (RT-PCR) which is a technique combining reverse transcription of RNA into DNA, sometimes called complementary DNA (Cdna) and amplifying the presence of specific DNA targets (virus) using polymerase chain reaction (PCR)..

But RT-PCR is a very advanced and sophisticated analysis that can only be performed, read and interpreted by a qualified medical diagnostic scientist working in a an advance research laboratory.

Not any Dick, Tom and Harry medical technician or a doctor can perform this analysis, and this may take days.

The second type of test that can be done is, instead of trying to detect for the antigen (virus) in the throat, is to look for antibodies already acquired by a person who is already ill with this virus or who has already been infected for many days but remains “healthy” and presented asymptomatically (no symptoms).

In this case, instead of a throat swab, a drop of blood from finger prick will do.

What we do is to look for antibodies (Immunoglobulin ((IgA, IgG, IgM, IgD…etc) elicited by the body in response to the infection.

But which fraction or sub-class fraction of these immunoglobulin is specific to this class of Coronavirus (Covid-19) I am not too sure, because any type of infections including bacterial will elicit any of these antibodies.

Again we are back to two problems on specificity and sensitivity..

In the case of sensitivity for antibodies for Coronavirus, we have to look at the duration since infection as it takes time for the body to produce the antibodies for them to rise for detection.

If the infection is mild or only just started a few days ago, we may not be able to pick it up.

In short, the amount of antibodies stimulated may not be in sufficient amount to be detected, thus giving a false negative.

Diagnosis of corona virus infection is very challenging and difficult at this moment in time for clinicians and medical scientists because it is so new.

Until we have better understanding and data, these two diagnostic approaches serves us well.

Least of all, we should not depend on symptoms like fever and coughs alone. Symptoms are only guidelines, not conclusive.

Sorry you have asked me these two very difficult questions for which I have no practical experience.

This is my academic level best in answering. I hope it helps

As to your other question on the best approach in treatment or on how to enhance our body’s immunity to this disease, can I answer that later because actually I am in this midst of doing some astronomical calculations on the size of Earth, Oort Cloud and the comparative dimensions to the edge of an Observable Universe, and their relationship to whether or not life cloud exists in other worlds – something that interests me far more than Coronavirus or medicine.

In fact, I am now having a headache calculating and re-calculating the astronomical data for hours now to ensure scientific accuracy.

So give me time for astronomical mathematics instead of suggesting some “cure” for this terrible infection that has claimed the lives of hundreds of thousands of people world-wide.

Kindly be patient. Let me think carefully first.

Thank you for your questions

Lim ju boo