On January 20, the World Health organization (WHO) issued an advisory for labs which process polymerase chain reaction (PCR) tests to detect SARS-CoV-2, the virus that causes COVID-19. The Maine Wire has previously covered Maine’s predominant use of a highly-sensitive PCR test and how it could generate lots of positive results from people who are neither sick nor infectious.
The recent WHO notice essentially serves as a reminder for technicians administering PCR tests to “read and follow the IFU (instructions for use) carefully to determine if manual adjustment of the PCR positivity threshold is recommended by the manufacturer.”
At first glance, this notice might seem like a nothingburger, but upon deeper reflection, the burger becomes a bombshell. Warning that “as disease prevalence decreases, the risk of false positive increases,” the advisory asserts that “careful interpretation of weak positive results is needed.”
Acknowledging the link between Ct value and viral load, WHO affirms what The Maine Wire reported in November: “The cycle threshold (Ct) needed to detect virus is inversely proportional to the patient’s viral load.” This means a high level of amplification of a particular sample means a smaller amount of virus.
PCR tests are very accurate for forensic uses to determine if genetic fragments are present in a sample, not to determine their prevalence or vivacity. As it turns out, this aspect of the test is critically important to understanding who is actually infected with SARS-CoV-2 to a level where they risk spreading it to others.
“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,” the advisory reads.
Here, the world’s top public health organization recognizes that a positive PCR test does not automatically make one a “case” of COVID-19. If a patient’s test results show a positive, but they are healthy and not showing symptoms of an infection, WHO is urging practitioners to retest with an alternative technology to PCR, which might be an antigen or lateral flow test.
They mention that PCR tests should be used “as an aid for diagnosis,” something to be taken into account by a medical doctor when determining if someone has contracted the virus and should isolate.
Since positive test results determine the count of “cases,” the cycle threshold limit for PCR tests significantly affects the number of cases that exist. These are the numbers reported from state public health officials’ daily news updates which are leveraged by the governor to ratchet up her unilateral emergency orders.
In effect, the latest WHO notice warns against diagnosing a healthy person with COVID-19 if a positive PCR result is the only evidence. Credible scientists have determined over and over again that the risk of asymptomatic transmission is near zero. Logic follows then that we should not be conducting mass testing of healthy people either, since they are not driving the epidemic, as Dr. Anthony Fauci said last year.
State leaders have inflicted an immense amount of stress and fear into the public over the past 10 months. Most of it was based on faulty assumptions and the willful ignorance of immunology and biology.
It is time for politicians and public health officials to talk us down from the ledge.
