Former Human Genome Project team leader on PCR testing

[CoastalVADawg]

 

[stray]

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I have no idea what that means but doesn't sound good. LOL

 

[D Dawg]

I have no idea what that means but doesn't sound good. LOL

Ha me either. I did read where Imperial College, of the 2+ million US death projection, is now saying antibodies wear off after 6-12 months making herd immunity and vaccination extremely difficult to achieve. Essentially its similar to the common cold. If they are right then basically we will just live with this and have to rely on treatments whether OTC or prescription.

 

[JackRussellDawg]

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Is this the same gnome that does those travel commercials?

 

[CoastalVADawg]

Ha me either. I did read where Imperial College, of the 2+ million US death projection, is now saying antibodies wear off after 6-12 months making herd immunity and vaccination extremely difficult to achieve. Essentially its similar to the common cold. If they are right then basically we will just live with this and have to rely on treatments whether OTC or prescription.

Antibodies only last for a few weeks to months - that’s nothing new. Cellular and innate immunity are what provide long-term protection and it has already been demonstrated that SARS-specific T-cells last for over 10 years. We also know that there is cross-reactivity with T-cells generated in response to human coronaviruses that cause the common cold. The problem with all the models that predicted mass casualties is they assumed everyone in the population was susceptible. We now know about 40-60% of of the population have pre-existing cross-reactive T-cells.

 

[Professor Dawghair]

SARS-specific T-cells last for over 10 years

Are the vaccines in development expected to create T-cell immunity?

 

[D Dawg]

Antibodies only last for a few weeks to months - that’s nothing new. Cellular and innate immunity are what provide long-term protection and it has already been demonstrated that SARS-specific T-cells last for over 10 years. We also know that there is cross-reactivity with T-cells generated in response to human coronaviruses that cause the common cold. The problem with all the models that predicted mass casualties is they assumed everyone in the population was susceptible. We now know about 40-60% of of the population have pre-existing cross-reactive T-cells.

So what’s the end game here? Virus fatigue? I’m well past that. It seems to me politicians are waiting on a knight on a white horse that’s not coming.

 

[Carpet City K9]

What does this have to do with the price of tea in China?

 

[MonolithicDawgX]

What does this have to do with the price of tea in China?

Bat farts!

 

[doug518]

Ha me either. I did read where Imperial College, of the 2+ million US death projection, is now saying antibodies wear off after 6-12 months making herd immunity and vaccination extremely difficult to achieve. Essentially its similar to the common cold. If they are right then basically we will just live with this and have to rely on treatments whether OTC or prescription.

They lost all credibility with their ludicrous death predictions

 

[Carpet City K9]

They lost all credibility with their ludicrous death predictions

According to Sleepy Joe, COVID has killed 210 million and guns have killed an additional 150 million since 2007.... there's actually only a couple million people in the US nowadays but the media is covering it up.... most of them live in Atlanta and drive constantly....

 

[HawtDawg2016]

I have no idea what that means but doesn't sound good. LOL

The way the PCR test works is that it amplifies small pieces of the viral material in successive steps. So 1 piece would become 2, 2 pieces become 4, 4 become 8 etc. eventually with enough pieces it becomes detectable. One of the problems with this technique is that it will also amplify things that are not from the virus as well (but to a lower level). After each round of replication the machine will check to see if it detects and positive signal which would correlate to virus being present. After about 33-34 rounds of replication (sometimes abbreviated CQ or CT) you will almost always start to get positive signal detected even if there was no virus present. Some testing facilities are doing up to 40 rounds of replication to see if they get a positive signal, and at that many rounds of replication you’re almost guaranteed to get something, even in negative controls. There’s another complication in that when a virus replicates itself it makes mistakes, so there is a lot of “junk” made by the virus which is not actually infectious or dangerous but could come up positive on the test.
What he’s pointing out is that there are scientists who have looked at what the threshold for detection by PCR should be in relation to if there is actually “live”, infectious virus present or not. They found that infectious virus can be detected if the CT value (number of PCR replications) is below 33, which is a standard cutoff for this type of test anyway. As my geneticist friend put it “anything above 32 is just junk”. So basically with current testing you are likely getting a lot of false positives just because the cutoff for the test is set too low. This doesn’t take into account that this test could also have some cross reaction with common cold viruses, which also appear to account for some of the positive tests (last I looked into that was a while ago, but a lab in Germany estimated about 15% of positive tests could be attributed to common cold viruses).

TLDR the PCR test isn’t the best way to tell if someone is infectious or should be isolated and we should have already put more R&D into better tests that are more affordable and can be done by the person at home (at least in his opinion).

 

[HawtDawg2016]

Antibodies only last for a few weeks to months - that’s nothing new. Cellular and innate immunity are what provide long-term protection and it has already been demonstrated that SARS-specific T-cells last for over 10 years. We also know that there is cross-reactivity with T-cells generated in response to human coronaviruses that cause the common cold. The problem with all the models that predicted mass casualties is they assumed everyone in the population was susceptible. We now know about 40-60% of of the population have pre-existing cross-reactive T-cells.

Antibodies fall under the umbrella of cellular immunity, along with T cells. Both can provide life long protection as T cells and the antibody producing B cells will survive long term and reactivate with subsequent infections. Innate immunity is not long lasting and is non specific. Most cells involved in innate immunity don’t live more than a few days to 2 weeks. Unfortunately protection is a lot more complicated than are there reactive T or B cells present, especially in the case of respiratory infections. There’s no way to know ahead of time how well a vaccine will work to protect against infection, but if there is an effective vaccine produced I’d bet that it’ll have to be given every year like flu (or at best every 2 years) to be effective long term.

 

[HawtDawg2016]

Are the vaccines in development expected to create T-cell immunity?

Current vaccines are focused on antibody mediated immunity for a number of reasons (1 big one being it’s easier to test for antibodies). That said most if not all of the vaccines should also generate some level of T cell immunity, but there are reasons to doubt that it will be very effective long term. Currently we don’t know if T cell or antibody mediated protection is better (or if both are about equal) for this particular virus.

 

[wstugamd]

The way the PCR test works is that it amplifies small pieces of the viral material in successive steps. So 1 piece would become 2, 2 pieces become 4, 4 become 8 etc. eventually with enough pieces it becomes detectable. One of the problems with this technique is that it will also amplify things that are not from the virus as well (but to a lower level). After each round of replication the machine will check to see if it detects and positive signal which would correlate to virus being present. After about 33-34 rounds of replication (sometimes abbreviated CQ or CT) you will almost always start to get positive signal detected even if there was no virus present. Some testing facilities are doing up to 40 rounds of replication to see if they get a positive signal, and at that many rounds of replication you’re almost guaranteed to get something, even in negative controls. There’s another complication in that when a virus replicates itself it makes mistakes, so there is a lot of “junk” made by the virus which is not actually infectious or dangerous but could come up positive on the test.
What he’s pointing out is that there are scientists who have looked at what the threshold for detection by PCR should be in relation to if there is actually “live”, infectious virus present or not. They found that infectious virus can be detected if the CT value (number of PCR replications) is below 33, which is a standard cutoff for this type of test anyway. As my geneticist friend put it “anything above 32 is just junk”. So basically with current testing you are likely getting a lot of false positives just because the cutoff for the test is set too low. This doesn’t take into account that this test could also have some cross reaction with common cold viruses, which also appear to account for some of the positive tests (last I looked into that was a while ago, but a lab in Germany estimated about 15% of positive tests could be attributed to common cold viruses).

TLDR the PCR test isn’t the best way to tell if someone is infectious or should be isolated and we should have already put more R&D into better tests that are more affordable and can be done by the person at home (at least in his opinion).

Bingo. This is a screening test at best. It doesn't mean you have the disease, but that a more specific test should be obtained. Also there is the pesky part about clinical symptoms. Without clinical symptoms there can be no diagnosis.