這篇文章 ( https://tinyurl.com/f4vecjwp ) 說,CT value ≤28 是用於 sequencing,不是用於是否紀錄為陽性的判斷。
As evidence for its claim that the U.S. CDC is “lowering their CT value when testing samples from suspected ‘breakthrough infections’” to “decrease the number of ‘breakthrough infections’ being officially recorded”, the article cited this statement on the CDC website:
“For cases with a known RT-PCR cycle threshold (Ct) value, submit only specimens with Ct value ≤28 to CDC for sequencing. (Sequencing is not feasible with higher Ct values.)”
This is a grossly inaccurate interpretation of the CDC guidance. The guidance applies to samples sent for genomic sequencing, which is a technique used to obtain the genetic sequence of the virus. This technique allows scientists to determine the virus’ lineage and identify variants and provides scientists with important information on how the virus is evolving and how mutations change the way the virus behaves. This information in turn helps to guide public health measures and vaccine development.
As is evident from the statement, the CDC didn’t alter the cycle threshold value for the PCR test used to identify presence of infection. The statement is relevant to genomic sequencing, which is an additional test used on samples that already tested positive for SARS-CoV-2 by PCR. The reason why this guidance is in place is because genomic sequencing requires a relatively large amount of the virus’ genetic material in the sample. Therefore, a sample with only trace amounts of the virus’ genetic material, which would show a high Ct value, wouldn’t be suitable for sequencing.
Not sequencing a sample doesn’t change the fact that someone tested positive for COVID-19 by PCR, meaning that the person is infected, making them a COVID-19 case. Therefore, this CDC guidance has no influence on the number of COVID-19 cases recorded, as the article claimed.
這篇文章 ( https://tinyurl.com/f4vecjwp ) 說,CT value ≤28 是用於 sequencing,不是用於是否紀錄為陽性的判斷。
回覆刪除As evidence for its claim that the U.S. CDC is “lowering their CT value when testing samples from suspected ‘breakthrough infections’” to “decrease the number of ‘breakthrough infections’ being officially recorded”, the article cited this statement on the CDC website:
“For cases with a known RT-PCR cycle threshold (Ct) value, submit only specimens with Ct value ≤28 to CDC for sequencing. (Sequencing is not feasible with higher Ct values.)”
This is a grossly inaccurate interpretation of the CDC guidance. The guidance applies to samples sent for genomic sequencing, which is a technique used to obtain the genetic sequence of the virus. This technique allows scientists to determine the virus’ lineage and identify variants and provides scientists with important information on how the virus is evolving and how mutations change the way the virus behaves. This information in turn helps to guide public health measures and vaccine development.
As is evident from the statement, the CDC didn’t alter the cycle threshold value for the PCR test used to identify presence of infection. The statement is relevant to genomic sequencing, which is an additional test used on samples that already tested positive for SARS-CoV-2 by PCR. The reason why this guidance is in place is because genomic sequencing requires a relatively large amount of the virus’ genetic material in the sample. Therefore, a sample with only trace amounts of the virus’ genetic material, which would show a high Ct value, wouldn’t be suitable for sequencing.
Not sequencing a sample doesn’t change the fact that someone tested positive for COVID-19 by PCR, meaning that the person is infected, making them a COVID-19 case. Therefore, this CDC guidance has no influence on the number of COVID-19 cases recorded, as the article claimed.
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