Rt - PCR test

[Dave G]

Just to make you aware that the test required for flying from the UK is a RT-PCR test.

 

I have heard that an airline at LHR is rejecting passengers with the ordinary, and more common, PCR test.  

 

 

 

 

 

[clivebaxter]

Never heard of it was is it?

[Gulfsailor]

The RT is just a step to make RNA into DNA. PCR can only be done on DNA. Since the coronavirus is an RNA virus any and all PCR tests done on it will be RT-PCR regardless what terminology is written on the document. 

[Dave G]

Some test providers differentiate between PCR tests and RT-PCR tests, and charge more for a RT-PCR test.

 

The important difference is that if your test certificate does not  state RT-PCR, you may not be allowed to board a plane.

 

 

 

[Lemsta69]

7 hours ago, Gulfsailor said:

The RT is just a step to make RNA into DNA. PCR can only be done on DNA. Since the coronavirus is an RNA virus any and all PCR tests done on it will be RT-PCR regardless what terminology is written on the document. 

this may be true but it means nothing to the common man. or the people at the check-in counter who are just following a script. so it's a bit obtuse for the test providers to call it "PCR" with they know the airline or immigration at the destination and are looking for "RT-PCR". 

[federicoP]

7 hours ago, Gulfsailor said:

The RT is just a step to make RNA into DNA. PCR can only be done on DNA. Since the coronavirus is an RNA virus any and all PCR tests done on it will be RT-PCR regardless what terminology is written on the document. 

I still do not understand if RT-PCR stands for Reverse Transcriptase-PCR or for Real Time-PCR , or maybe for both.....

[Dave G]

"An RT-PCR test, like the normal PCR test, uses swab samples from the nose and throat to find the Covid-19 virus. While an RT-PCR test will allow travellers into countries where a PCR test is an entry requirement, certain countries accept only RT-PCR tests."

 

Above was on one of the test clinic websites. Although it doesn't explain the scientific difference between the two, it does explain the importance of getting an RT - PCR test if required by the country you are travelling to. The Royal Thai Embassy London has stated that a RT-PCR test is required for entry into Thailand. 

 

[Sheryl]

RT = reverse transcription. It is a process whereby RNA is used ("transcribed") to produce DNA.

 

PCR tests identify the presence of DNA.

 

The COVID virus contains only RNA so it is impossible to do a PCR test for it without the RT step. All COVID PCR tests  are RT-PCR. There is no other way it can be done. The only time a PCR test can be done without the RT step is if it is identifying an organism that contains DNA. COVID does not.

 

However most non-medical people do not know this - certainly airline staff, Imm officers etc do not -- and labs do not always state "RT-PCR" on their reports. It will have been an RT-PCR though, for sure. So before using a particular lab find out how their results will be worded. If not including the phrase "RT-PCT" then ask if they can specify it.

 

Just a matter of wording, no difference in the tests, but given the way Thailand's requirements are phrased it is an important one.

 

 

 

 

[Dave G]

Sheryl,

 

The below link does suggest their are differences between the type of test.

 

As you said, the main point for travellers to Thailand is to ensure that the certificate will state RT-PCR before booking a test. All airlines will have been told only to allow people with negative RT-PCR tests to board. Ask to see a sample test certificate before booking.

 

 

https://www.enzolifesciences.com/science-center/technotes/2017/march/what-are-the-differences-between-pcr-rt-pcr-qpcr-and-rt-qpcr?/

[Sheryl]

2 minutes ago, Dave G said:

Sheryl,

 

The below link does suggest their are differences between the type of test.

 

As you said, the main point for travellers to Thailand is to ensure that the certificate will state RT-PCR before booking a test. All airlines will have been told only to allow people with negative RT-PCR tests to board. Ask to see a sample test certificate before booking.

 

 

https://www.enzolifesciences.com/science-center/technotes/2017/march/what-are-the-differences-between-pcr-rt-pcr-qpcr-and-rt-qpcr?/

Of course there is a difference between plain PCR and RT-PCR but what I was explaining is that all COVID PCRS are RT-PCR even if not explicitly stated as such.

 

It is a physical impossibility to do a COVID PCR without the initial RT step. Because the COVID virus does not contain any DNA, only RNA.

 

So it is nto a matter of needing a special sort of test, any place doing COVCID PCR is doing RT-PCR. But for entry into Thailand you need to be sure the results will clearly state RT-PCR.

 

 

[kawikasudo]

16 hours ago, Sheryl said:

Of course there is a difference between plain PCR and RT-PCR but what I was explaining is that all COVID PCRS are RT-PCR even if not explicitly stated as such.

 

It is a physical impossibility to do a COVID PCR without the initial RT step. Because the COVID virus does not contain any DNA, only RNA.

 

So it is nto a matter of needing a special sort of test, any place doing COVCID PCR is doing RT-PCR. But for entry into Thailand you need to be sure the results will clearly state RT-PCR.

 

 

I’m flying from Hawaii where one of the main healthcare is Kaiser Hospital and their PCR is an RT-PCR 

[partington]

On 11/20/2021 at 8:10 PM, federicoP said:

I still do not understand if RT-PCR stands for Reverse Transcriptase-PCR or for Real Time-PCR , or maybe for both.....

It's unfortunate that they have the same initials, and that some newspaper articles confuse the two. 

 

The abbreviation RT-PCR with reference to Covid tests always means reverse transcriptase PCR, because this is the only kind of PCR test that is able to detect Covid, as Sheryl pointed out above.

 

Real-time PCR refers to the kind of equipment used to read the PCR results - nowadays nearly all PCRs of any kind done in a high throughput lab would be real time PCRs, so all Covid PCR tests will also be real time PCRs. However while all Covid tests MUST be reverse-transcriptase PCRs, they are not obligatorily real time PCRs, though they almost certainly are as well.

 

A PCR test consists of around 40 temperature cycle repeats, a cycle being, for example 94°C for 20 secs, followed by 68°C for 30sec. A real time PCR measures the amount of detected product during each cycle, as it is happening, so is faster. Earlier methods relied on waiting until all 40 cycles are done and then measuring the amount of detected product afterwards.

 

So the correct description of a Covid test is a "Real -Time RT-PCR". You can see this kind of terminology used by the FDA to describe other diagnostic tests- e.g.here in the FDA listed approved PCR test for 

Dengue:

Dengue virus

CDC DENV-1-4 Real-Time RT-PCR Assay

Centers for Disease Control and Prevention

K113336

 

 source: https://www.fda.gov/medical-devices/in-vitro-diagnostics/nucleic-acid-based-tests#microbial