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.
Tests with thresholds so high may detect not just live virus but also genetic fragments, leftovers from infection that pose no particular risk — akin to finding a hair in a room long after a person has left, Mina said.
Any test with a cycle threshold above 35 is too sensitive, agreed Juliet Morrison, a virologist at the University of California, Riverside. “I’m shocked that people would think that 40 could represent a positive,” she said.
A more reasonable cutoff would be 30 to 35, she added. Mina said HE WOULD SET THE FIGURE AT 30, OR EVEN LESS! (emphasis added) Those changes would mean the amount of genetic material in a patient’s sample would have to be 100-fold to 1,000-fold that of the current standard for the test to return a positive result.
The Food and Drug Administration said in an emailed statement that it does not specify the cycle threshold ranges used to determine who is positive, and that “commercial manufacturers and laboratories set their own.”
The Centres for Disease Control and Prevention said it is examining the use of cycle threshold measures “for policy decisions.” The agency said it would need to collaborate with the FDA and with device manufacturers to ensure the measures “can be used properly and with assurance that we know what they mean.”
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www.ecdc.europa.eu
Criminal fraud.
Tests with thresholds so high may detect not just live virus but also genetic fragments, leftovers from infection that pose no particular risk — akin to finding a hair in a room long after a person has left, Mina said.
Any test with a cycle threshold above 35 is too sensitive, agreed Juliet Morrison, a virologist at the University of California, Riverside. “I’m shocked that people would think that 40 could represent a positive,” she said.
A more reasonable cutoff would be 30 to 35, she added. Mina said HE WOULD SET THE FIGURE AT 30, OR EVEN LESS! (emphasis added) Those changes would mean the amount of genetic material in a patient’s sample would have to be 100-fold to 1,000-fold that of the current standard for the test to return a positive result.
The Food and Drug Administration said in an emailed statement that it does not specify the cycle threshold ranges used to determine who is positive, and that “commercial manufacturers and laboratories set their own.”
The Centres for Disease Control and Prevention said it is examining the use of cycle threshold measures “for policy decisions.” The agency said it would need to collaborate with the FDA and with device manufacturers to ensure the measures “can be used properly and with assurance that we know what they mean.”
Your coronavirus test is positive. Maybe it shouldn’t be
Some of the nation’s leading public health experts are raising a new concern in the endless debate over coronavirus testing in the United States: The standard tests are diagnosing huge numbers of people who may be carrying relatively insignificant amounts of the virus.
m.bdnews24.com
Diagnostic testing and screening for SARS-CoV-2
Diagnostic specimens, antibody testing, storage and shipping of specimens, testing methods and genetic characterisation of SARS-CoV-2, detection of variant viruses, neutralisation assays and antigenic characterisation of SARS-CoV-2 and biosafety.
Criminal fraud.
