The PCR does not test for Covid 19. Covid 19 is a disease— COrona VIrus Disease 19— which is caused by the SARS-CoV 2 virus when it replicates inside your body.
Definition is important. What are you actually measuring?
The number of virions (individual virus) you inhale will largely determine whether you get sick. You can inhale hundreds or thousands of virions and not get covid infection. The probability of infection goes up with the amount of virus you are exposed to.
If they test for 30 nucleotides in a row (they probably test for several segments this long in the PCR) the number of permutations is 430 which is around 1 SEXTILLION.
There are about 6 billion base pairs in the human genome so the number of possible strands of mRNA 30 nucleotides long that could possible “show up” would be less than 6 billion.
1 sextillion/6 billion is roughly 200 million.
1 in 200 million
The chance that this sequence would randomly show up in a person should be considerably less than that. That would be if human genome was really random from person to person, which it isn’t.
You cant just root around in people long enough an find a 1 in sextillion sequence.
The issue is trace amounts of virus unlikely to cause infection are leading to positive PCRs and erroneous case counts.
>The PCR does not test for Covid 19.
PCR tests are used to diagnose covid19
https://www.health.harvard.edu/blog/which-test-is-best-for-covid-19-2020081020734
Diagnostic tests for current infection
If you want to know if you are currently infected with the COVID-19 virus, there are two types of tests: molecular tests and antigen testing.
Molecular tests (also called PCR tests, viral RNA tests, nucleic acid tests)
How is it done? Nasal swabs, throat swabs, and tests of saliva or other bodily fluids.
Where can you get this test? At a hospital, in a medical office, in your car, or even at home (the FDA recently granted EUA for a home molecular test that requires no prescription).
What does the test look for? Molecular tests look for genetic material that comes only from the virus.
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> PCR tests are used to diagnose covid19
You are missinng the crux of the entire debate. Really.
They are saying the levels of the virus likely to lead to infection will show up after 25 or 30 cycles.
If you only can get a positive after 35 or 40 cycles, the subject has a quantity of virus that will not likely lead to infection! So, according to some experts, we shouldn’t care about those positives.
They are saying the PCR test will work better as a test for infection if you reduce it’s sensitivity.
Confirmation of infection would be if your viral load increased on a subsequent PCR after 48 hrs or if you got symptoms.
You don’t need any other test. Antigen test wont work for at least 2 or 3 weeks. You need to correlate postive test result at 25 cycles (or 30 or 35) to probability of increased viral load after a second subsequent test, or development of symptoms or development of antigen. Then you can gauge the goodness of the PCR test at various cycle thresholds as a predictor of contagiousness or disease state.
>They are saying the levels of the virus likely to lead to infection will show up after 25 or 30 cycles.
No that's not what they say
https://www.rt.com/op-ed/507937-covid-pcr-test-fail/
>This is not the first challenge to the credibility of PCR tests. Many people will be aware that their results have a lot to do with the number of amplifications that are performed, or the ‘cycle threshold.’ This number in most American and European labs is 35–40 cycles, but experts have claimed that even 35 cycles is far too many, and that a more reasonable protocol would call for 25–30 cycles. (Each cycle exponentially increases the amount of viral DNA in the sample).
>Earlier this year, data from three US states – New York, Nevada and Massachusetts – showed that when the amount of the virus found in a person was taken into account, up to 90 percent of people who tested positive could actually have been negative, as they may have been carrying only tiny amounts of the virus.
>The Portuguese judges cited a study conducted by “some of the leading European and world specialists,” which was published by Oxford Academic at the end of September. It showed that if someone tested positive for Covid at a cycle threshold of 35 or higher, the chances of that person actually being infected is less than three percent, and that “the probability of… receiving a false positive is 97% or higher.”
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