美國CDC改變PCR檢驗的CT值


2021/06/30


美國CDC之前PCR檢查設定:CT=40上下

美國CDC目前PCR檢查設定:

已打過疫苗者:CT 小於28 

沒打過疫苗者:CT=35

~~~~

貓膩在於「打過」和「沒打過」疫苗的人用的CT設定值不一樣!!

經過這麼一條調整(把機器調得不敏感一點),結果會怎樣?答案:

打疫苗會有效,因為機器不敏感,於是乎新冠病毒陽性的比例自然會降低。

於是乎:疫苗打越多越有效! 

留言

  1. 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.

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