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Bill Rice, Jr.'s avatar

An example that proves this quote: “…. half of social sciences these days seems to consist of deliberately impenetrable jargon to occlude and obscure meaning (if, indeed, there is any meaning at all) so it seems to be seen as some sort of feature rather than a bug. but “oh, that’s unparsable and/or incomprehensible to me; it must be profound” is a truly dangerous basis for intellectual belief ..."

A year or so ago, I emailed a contact at the Alabama’s Governor’s office and asked him: “If anyone in the Governor's office can provide data on the "cycle thresholds" used to determine "positive cases" in the PCR tests?”


Mr contact in the governor’s office forwarded my question to the Alabama Department of Public Health (ADPH) and sent me the reply he received to my simple question on the PCR cycle thresholds.

The response was written by Dr. Karen Landers, the main spokesperson for the ADPH. Can anyone discern my answer from this scientific gobbledy-gook and obfuscation? My “answer:” …

“Real Time polymerase chain reaction (RT-PCR) assays for COVID 19 are approved for use under Emergency Use Authorization (EUA) by the FDA. A variety of testing assays, such as Thermo Fisher TaqPath, GeneXpert Xpert® Xpress, and Hologic Aptima SARS-CoV-2, are used and reporting of results vary from manufacturer to manufacturer.

“A RT-PCR assay can help determine a desired target based on specific genetic material (such as for COVID-19) present in a sample. During the assay, the genetic material from the sample is amplified exponentially over a specific number of cycles and the amplification is monitored by changes in an associated fluorescent signal. There is also a background level established for each assay to help distinguish if from the fluorescent signal.

“The intensity of the fluorescence increases as the number of cycles increases throughout the assay. The point where the number of cycles required for the fluorescent intensity to cross above the background level is known as the cycle threshold (CT). There is a correlation between the CT value and the amount of genetic material present in a specimen. The more genetic material present, the lower the CT value. The less genetic material present, the higher the CT value. Reporting for a positive assay is pre-determined by performance studies to indicate the value for a cutoff for the CT.

“RT-PCR tests that have received EUA from the FDA for COVID-19 as of October 23, 2020, are qualitative tests. This means that the test reflects the presence or absence of the viral genetic material but not the actual CT value. These platforms have predetermined CT values that are not reported. The manufacturer regards them as proprietary information which they do not disclose.

“So, there is no CT value to be used to determine how infectious a person is or when the person can be released from isolation or quarantine.


“The results for a RT PCR assay can be affected by factors other than the amount of virus in the specimen. Collection and storage of the specimen can affect results as well as when the specimen was collected in relation to when the person became ill.

“The steps used to process the genetic material, the specific genetic target being measured, and the amount and type of the patient sample used varies among RT-PCR tests.Therefore, the CT values will differ between the assays that generate them.

“In addition, not all COVID-19 tests report results using CT values. Some manufactures such as Hologic, whose COVID-19 assay has been widely used, report their results in relative light units (RLUs). However, the reporting from the instrument is negative or positive based on pre-determined RLU values. A method of synchronizing CT values across manufacturers is not available. “

… Basically, nobody knows the CT number of the PCR tests used to determine “positive cases.” Our trusted public health agencies know the answer ... they are just not willing to give it to the public they supposedly serve.

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Sarah Thompson's avatar

I live on a small, rocky island, and there are many low spots in the roads near tidal marshes. They put these scare meters next to the road to measure the rise in water levels (good luck 6th graders!) and now, whenever the roads are flooded because the moon and the wind and the weather line up just right, it's absolute proof that the entire island will be underwater if we don't stop using plastic straws.

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