Here is a fascinating story.
The World Health Organization (WHO) recently requested that laboratories across the globe decrease the cycle count in PCR COVID-19 testing. This would result in fewer positives.
From the WHO:
Users of IVDs must read and follow the IFU carefully to determine if manual adjustment of the PCR positivity threshold is recommended by the manufacturer.
WHO guidance Diagnostic testing for SARS-CoV-2 states that careful interpretation of weak positive results is needed (1). The cycle threshold (Ct) needed to detect virus is inversely proportional to the patient’s viral load. Where test results do not correspond with the clinical presentation, a new specimen should be taken and retested using the same or different NAT technology.
WHO reminds IVD users that disease prevalence alters the predictive value of test results; as disease prevalence decreases, the risk of false positive increases (2). This means that the probability that a person who has a positive result (SARS-CoV-2 detected) is truly infected with SARS-CoV-2 decreases as prevalence decreases, irrespective of the claimed specificity.
Most PCR assays are indicated as an aid for diagnosis, therefore, health care providers must consider any result in combination with timing of sampling, specimen type, assay specifics, clinical observations, patient history, confirmed status of any contacts, and epidemiological information.
This comes as Amazon has offered its support to the Biden team with vaccine rollout, as well as Governor Andrew Cuomo (D-NY) saying that the economy needs to reopen.
There is a seismic shift going on, and it isn’t surprising one bit.
(H/T Target Liberty)
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