1/All Sars-Cov-2 PCR tests are designed around the endpoint established by FDA in authorizing the first PCR test by CDC that specified positive control at Ct <40. 
2/Most mfr use 35-40 as the threshold limit so variations among Ct results are likely at a similar level for most tests
scienceopen.com/document_file/…
scienceopen.com/document_file/…
3/Variations are easily resolved with calibrated standard curves of viral copies/ml vs Ct for each test. FDA does not require this for some reason
4/So many studies are looking at Ct of samples vs ability of samples to be cultured, so don’t seem scared off by the variance. Also CDC specifies Ct<28 for samples to be sent fir full genome sequencing knowing there is some variation between test kits
academic.oup.com/cid/article/72…
academic.oup.com/cid/article/72…
5/Fauci himself said “if you get a cycle threshold of 35 or more … the chances of it being replication-confident are minuscule.....So, I think if somebody does come in with [a Ct value of] 37, 38, even 36, you got to say, you know, it’s just dead nucleotides, period.”
6/
“Most tests set the limit at 40, a few at 37. This means that you are positive for the coronavirus if the test process required up to 40 cycles, or 37, to detect the virus......Any test with a cycle threshold above 35 is too sensitive”
nytimes.com/2020/08/29/hea…
“Most tests set the limit at 40, a few at 37. This means that you are positive for the coronavirus if the test process required up to 40 cycles, or 37, to detect the virus......Any test with a cycle threshold above 35 is too sensitive”
nytimes.com/2020/08/29/hea…
7/As for higher Ct threshold to account for higher viral load in lungs I am going to have to ask you to link to source. In any event, if viral replication is occurring in lungs one can be confident nasal swabs viral load will be moderate to high
8/Pre-symptomatic and asymptomatic spread is not proven to be a significant driver of epidemics. Fauci himself said that in 2020. There is little evidence this is a major driver for COVID spread, especially with masks snd Social distancing
9/Most doctors report most patients are free of replicating virus 7-9 days after symptom onset. The COVID disease persisting after the viral replication phase is due to lung damage and inflammation from cellular and viral debris
10/Positive tests at high Ct that may persist for weeks after recovery is mostly due to viral debris and not replication competent virus.
11/Testing asymptomatic persons with PCR tests where positive tests are defined at high Ct levels is a big problem
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