[DigitalOne]

Originally Posted by fordday

Please see the sevasindhu website for the latest rules from MoHFW, GoK.

Thanks! This helped.

In-laws came back from Dubai couple of days back. They were tested negative in Dubai, before boarding, and temperature scan in Bengaluru. I am not sure what test was used in Dubai - they used blood sample (definitely not PCR). They had to report at Dubai airport 5 hours before scheduled departure.

They will be in Institutional quarantine for a week in a hotel in Bangalore. Transport (bus) from airport to hotel was arranged by hotel.

Overall an 17 hour ordeal.

[vivek95]

Originally Posted by DigitalOne

. I am not sure what test was used in Dubai - they used blood sample (definitely not PCR).

This mostly has to be the rapid antibody test.

[Lobogris]

Originally Posted by vivek95

This mostly has to be the rapid antibody test.

Is it possible for a normal person to get an antibody test done to check if they have had this virus? Which institutions are capable of doing such tests?

[vivek95]

Originally Posted by Lobogris

Is it possible for a normal person to get an antibody test done to check if they have had this virus? Which institutions are capable of doing such tests?

No. Only RT-PCR, CBNAAT and TrueNAT tests can be done all of which are antigen/virus detection tests. In India, antibody tests cannot be requested by the general public on their own.

[Nalin1]

Originally Posted by mohansrides

I have said this since the beginning. Now these guys are saying it.

https://www.hindustantimes.com/india...tuXWiUEiI.html

To be clear, these guys are not from a “left wing” news organisation.

We decided to kick Corona's backside with a lockdown and send it flying into orbit.

But the virus just stuttered a bit and continued on its rampage.

Now we have accepted defeat after the lockdown broke our own leg.

[GTO]

Oh My God! The pleasure of driving. Had some work, so took the Jeep out (sunny skies, no rain). Was so good to reconnect with her. Automotive life is slowly getting back to normal. Spotted a nicely modded Octavia vRS, a Fortuner with the same tyres as my Jeep...and the Official Review cars are coming in soon.

[turbo]

So the lockdown unofficially ends tomorrow, with all offices opening (except for MH. Poor you)

The lack of activity in this thread shows everyone's too busy ironing their shirts.

[Turbanator]

Originally Posted by vivek95

In India, antibody tests cannot be requested by the general public on their own.

What will be the logic for such restriction? I am sure people who came in close contact with positive cases will like to get this besides, it can give an idea of approximate population who came out of this without even noticing.

[Aditya_Bhp]

Originally Posted by Turbanator

What will be the logic for such restriction? I am sure people who came in close contact with positive cases will like to get this besides, it can give an idea of approximate population who came out of this without even noticing.

Antibody card tests have failed in India. They are not very sensitive and also give false negatives too. ICMR imported the first set of card test from China, which promised results in 30 minutes, but most of them failed to detect the presence of Antibodies even in Symptomatic Covid patients. Hence they were sent back.

Now, we have locally made Antibody ELISA testing kits, and the states will start mass screening from tomorrow using the ICMR developed ELISA kits. They are cheap and fast, its not confirmatory but this can be used to screen mass number of people. Do remember, Antibody test uses Blood samples.

The confirmatory test remains RT-PCR. Usually takes 4 to 5 hours for a test, but because of the logistics, packing and all, results take around 24 to 36 hours.

For emergency testing, ICMR has approved CBNAAT, which is a catridge based test to detect Nucleic Acids in a sample. Originally designed for detecting TB, the software has now been modified to detect Covid19 and the results come out in 30 minutes, the draw back is the cost, each test can cost upto Rs.10000.
Recently India had developed a low cost model of the CBNAAT, the TrueNAT, its almost equally good as CBNAAT but is a lot cheaper and costs just Rs.1500 for a test. Also TrueNAT is already available in most district level govt hospitals, they are now being modified to detect Covid19. Another advantage, the virus is lysed here, hence there is no risk of spread of the disease from mishandling the sample.

[Sutripta]

Originally Posted by vivek95

No. Only RT-PCR, CBNAAT and TrueNAT tests can be done all of which are antigen/virus detection tests. In India, antibody tests cannot be requested by the general public on their own.

I thought these were all PCR tests. What is the difference between PCR tests and antigen tests?

Sutripta

[ninjatalli]

Originally Posted by Sutripta

I thought these were all PCR tests. What is the difference between PCR tests and antigen tests?

Sutripta

A starting point - https://www.npr.org/sections/health-...h-one-you-mean

Originally Posted by Aditya_Bhp

Now, we have locally made Antibody ELISA testing kits, and the states will start mass screening from tomorrow using the ICMR developed ELISA kits.
...
For emergency testing, ICMR has approved CBNAAT, which is a catridge based test to detect Nucleic Acids in a sample.
...
Recently India had developed a low cost model of the CBNAAT, the TrueNAT, its almost equally good as CBNAAT but is a lot cheaper and costs just Rs.1500 for a test. Also TrueNAT is already available in most district level govt hospitals, they are now being modified to detect Covid19.

Thanks - but this is more confusing now! What happened to all the noise and congratulatory messages that were made around Mylabs testing kits ~2 months ago?

I'm guessing if we go to a govt or private lab today, we still get only the PCR test with a TAT of ~2 days. Is there a change going forward for the tests to be one of these above? i.e. an initial test with an antibody or antigen kit and if positive, then a PCR test of sorts?

~~~~~

Not sure if it is only me, but there have been so many news about different testing kits being approved as well as vendors being approved to mass-produce; and yet I keep seeing/reading twitter stories by actual folks who are sent back saying there aren't tests available, as well as facing other issues.

- Recently a friend (Mumbai) shared about how a +ve case was identified in his society. The team that arrived was not ready to test the other family members; on a further push from the society, it was shared that the team was told to make such decisions basis the family's health and advise quarantine for the entire family if they were asymptotic. This saves the # of tests required as well as keeps the # of infected low. No idea if this the right approach.

- A surgeon in his society reconfirmed the same at the (Mumbai) hospital he works.

- I spoke to my parents (Chennai) to check the local situation with a relative (doctor) who's active in one of the leading hospitals of Chennai. She confirmed that beds are next to none across all the govt hospitals and private hospitals would easily charge up a huge bill assuming if one had to spend the entire quarantine period in the hospital with ICU requirements and similar. Her advice to my mom - stay put at home. As much as possible.


Edit:

Originally Posted by Sutripta

It would be great if you could explain it in language we laymen would understand. Esp. how CBNAAT/ TrueNAT works.

Sutripta

^^Please read my post again. That's why I said it's a starting point.
More than just language, I'd pay to get the visibility, especially what's the local scene, if I or someone had to get a test done tomorrow.

[Sutripta]

Originally Posted by ninjatalli

A starting point - https://www.npr.org/sections/health-...h-one-you-mean

It would be great if you could explain it in language we laymen would understand. Esp. how CBNAAT/ TrueNAT works.

Originally Posted by ninjatalli

More than just language, I'd pay to get the visibility, especially what's the local scene, if I or someone had to get a test done tomorrow.

Don't quite get what you are saying.

Sutripta

[Aditya_Bhp]

Originally Posted by ninjatalli

Thanks - but this is more confusing now! What happened to all the noise and congratulatory messages that were made around Mylabs testing kits ~2 months ago?

I'm guessing if we go to a govt or private lab today, we still get only the PCR test with a TAT of ~2 days. Is there a change going forward for the tests to be one of these above? i.e. an initial test with an antibody or antigen kit and if positive, then a PCR test of sorts?

Mylabs, is a Pune based company that makes indigenous Rapid RT-PCR testing kits. They are slightly faster compared to conventional RT-PCR for processing the test. The actual test takes around 3 to 4 hours, but results are delayed and are expensive because-
The swab has to be taken by a person in PPE, and should be kept in a VTM. The person who takes the swab has to upload the details on the mobile app. Then this has to be sealed using 3 layers of covering, then they are to be transported to a testing lab.

Lab technicians sitting there will be in full PPE, and will take out the sample carefully after removing the packaging. Then the samples are processed on the RT-PCR machine. Basically a PCR multiplies the nucleic acid, the nucleic acid is obtained using a Nucleic acid extractor. Once its multiplied by approximately 20 times, the machine looks for certain sequences on the RNA which are characteristic of Covid 19. If its found, then its positive.

The advantage is that RT PCR can detect even minute quantities of viruses, but this is also a disadvantage, because, even if a person has very little viral load, which may be harmless, it comes as positive.

So even if we use Rapid RT PCR kits, the actual time taken and effort needed is a lot more, because of the complex nature and dangers associated with working on a live virus sample, and in the end results take 24 to 48 hours.

Also, even if kits are plenty, there is trained staff needed to process the samples. A lab technician in full PPE can work only for 4 hours, hence this also slows down the process.

If you go to a govt/private lab today, they will test you using PCR kits/CBNAAT/TrueNAT kits. You can find a list of Labs and their methods on the ICMR website, which will be updated daily.

The issue with the Antibody testing is that, so far none are accurate. The best ones for Covid19 are made by US based Abbott, but even they guarantee a 90% accuracy only. The antibody card tests are just like the Rapid tests used for Dengue or Leptospirosis, results will be quick but still aren't accurate. But then if a patient has clinical features suggestive of dengue and the card test is positive, then we need not do the ELISA test.

Antibody tests using ELISA kits are more accurate. ICMR has recently developed an indigenous ELISA testing kit. Testing using these kits are meant to start tomorrow. We will get to know accurate they are starting tomorrow. Its a lot cheaper, faster, and safer to use ELISA based testing methods. Results can come in around 6 to 8 hours vs the 24 hours presently. How good these kits are, we have to wait and watch over the next 1 week.

So yes, if these new tests are accurate enough, then ICMR can recommend using the ELISA kits as a routine test or an initial screening test and reserve the more expensive and time consuming RT-PCR only for the confirmation whether in doubt.

Originally Posted by Sutripta

It would be great if you could explain it in language we laymen would understand. Esp. how CBNAAT/ TrueNAT works.

Sutripta

CBNAAT was originally designed to diagnose Tuberculosis. Its a very good and quick test to detect TB. TrueNAT is basically a low cost, locally made CBNAAT.

Because India is a TB hotspot, such machines are available in plenty in govt as well as private.

How it works in Covid 19?

A sample is obtained from a patient. The sample is then processed and the virus is lysed. This is the major difference vs RTPCR, here the virus has been made inactive by lysing it. Now the sample with the lysed virus is kept in a catridge in a machine after further processing.

ICMR has modified the original software, meant to detect TB, to also detect a specific gene on the Covid 19 virus. So the computer looks for this specific gene in the sample. If its there, the sample contains SARS COV2 and the patient is declared positive.

This is in simple terms. Hope its understandable.

[vivek95]

Originally Posted by Sutripta

I thought these were all PCR tests. What is the difference between PCR tests and antigen tests?

Sutripta

Hello

Very sorry that I am busy, now out for lunch from my duty. But I can see other members helping you out on this. Dr. Aditya ( @Aditya_bhp) has been elaborating nicely. Basically, all these are PCR based tests itself. I mean Nucleic acid amplification test ( NAT) is the basic principle and PCR ( polymerase chain reaction ) is the mechanism involved to amplify the genetic material. CBNAAT and TrueNAT are all PCR based tests itself all of which detect presence of viral genetic material. Will list out the differences later.

The real 100% determinant test to identify presence of actual virus is by way of growing the blood sample in culture media. You might have read about PCRs picking up dead fragments of SARS--Cov2 in S. Korea, Singapore and showing up as positive. Thus, an active virus can be conclusively determined by way of culture but this is highly time consuming method.

[Sutripta]

Originally Posted by Aditya_Bhp

CBNAAT was originally designed to diagnose Tuberculosis. Its a very good and quick test to detect TB. TrueNAT is basically a low cost, locally made CBNAAT.
...
This is in simple terms. Hope its understandable.

Originally Posted by vivek95

Basically, all these are PCR based tests itself.

Thanks Aditya and Vivek.

So correct me if I'm wrong in my understanding, but essentially it the difference is working with a live virus vs working with a deactivated one?

If so, some questions
Where does the antigen part come in?
The time taken - PCR is time consuming because amplification needs repeated (heat cool enzyme etc) cycles to get usable/ workable amounts of genetic material. How do the rapid tests do it rapidly?
TB is a bacteria, not virus. Don't bacteria have a much more complex genetic structure?

Sutripta