Coronavirus

New studies on COVID-19 testing underscore need for greater transparency in Maine

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Maine Policy Institute has previously noted the potential pitfalls of relying on a single health authority, especially one subject to political consequences, for diagnosing disease among the people. We have also reported on the highly sensitive testing process that many US states and governments around the world use to identify cases of COVID-19: polymerase chain reaction, or PCR.

PCR is a process of amplification. By culturing genetic material present in a patient’s sample, the test effectively doubles the amount of virus in the sample with every amplification cycle. The test runs until it identifies the virus it seeks. The number of cycles needed to register a positive test is called the cycle threshold (Ct) value and different tests for COVID-19 run to different Ct levels. 

PCR is used in a variety of forensic situations to determine if fragments of RNA, or the genetic material of a particular virus, exist in a sample. It is considered the gold standard of viral identification processes, but even its inventor famously said “quantitative PCR is an oxymoron” because it cannot determine whether a patient is infectious or not.

The lower the cycle threshold value in a positive result, the greater the amount of virus in that sample. As recent studies on COVID-19 testing show, this likely also corresponds to the likelihood of a patient’s infectiousness at the time the sample is taken. 

A study out of Oxford University and published in Clinical Infectious Diseases this month reviewed the results of 22 studies on PCR test results for SARS-CoV-2, the coronavirus that causes COVID-19. The authors looked into the likelihood of active virus in a sample, as well as other variables that could influence the interpretation of a test such as days from symptom onset. They concluded:

“Complete live viruses are necessary for transmission, not the fragments identified by PCR. Prospective routine testing of reference and culture specimens and their relationship to symptoms, signs and patient co-factors should be used to define the reliability of PCR for assessing infectious potential. Those with high cycle threshold are unlikely to have infectious potential.”

They also note that “Six of eight studies reported detectable RNA for longer than 14 days but infectious potential declined after day 8 even among cases with ongoing high viral loads.” This is significant because the US CDC reports that even though viral fragments may remain in the respiratory tract up to three months later, the vast majority of patients are not infectious past 10 days after symptom onset. This might also indicate why the CDC recently revised its recommended quarantine for COVID-19 from 14 days to 10 days.

Research funded by the French Government and published in Clinical Infectious Diseases analyzed the results of more than 3,500 PCR tests and found that in those which cutoff at 25 cycles of amplification, up to 70% of samples contained live virus. At 30 cycles, that number dropped to 20% and at 35 cycles, they estimated that less than 3% of samples contained live, active virus capable of spreading infection.

Further strengthening the connection between Ct values and infectiousness, authors of a study published in Eurosurveillance, a prominent European scientific journal, “observed a strong relationship between Ct value and ability to recover infectious virus” in COVID-19 PCR results from England in early 2020. As Figure 2 from that study shows below, once a test approaches 25 cycles, confidence in that sample’s amount of live virus drops significantly. After 35 or 40 cycles, confidence quickly approaches zero.

Dr. Anthony Fauci, Director of the U.S. National Institute of Allergy and Infectious Diseases, presented a similar idea in a July interview. He mentioned that any positive test result obtained after 35 cycles is “just dead nucleotides” and likely not infectious. 

Reporting earlier this year, The New York Times noted that most tests in the United States run to 40 cycles, while a few stop at 37. The Times found that “In Massachusetts, from 85 to 90 percent of people who tested positive in July with a cycle threshold of 40 would have been deemed negative if the threshold were 30 cycles.” 

For context, the difference between 30 cycles and 40 cycles is the difference between 2-to-the-30th power and 2-to-the-40th-power, or a factor of 1,000. Maine CDC uses a test that amplifies all the way to 45 cycles, a test 1,000-times more sensitive than what Fauci and many other epidemiological researchers believe is reasonable.

Cycle threshold data is public record, which is why Maine Policy has requested Maine CDC provide this data pursuant to Maine’s Freedom of Access Act (FOAA). CDC estimates that fulfilling the request will take three months after the termination of Gov. Mills’ Civil State of Emergency declaration. Until then, Mainers must take media reports of total COVID-19 cases with a grain of salt. 

The question becomes: what interest does the state have to employ people in the pseudo-scientificprivacy-invading scheme of contact tracing if a test indicates the patient is not infectious?

Understanding the limitation of PCR to diagnose COVID-19 is crucial to understanding the true spread of this virus, for which our freedoms to worship and assemble have become the scapegoat. If—contrary to the statements of top administration officials—only 10%, 3%, or even 1% of our positive tests were actual “cases,” the pandemic would look much different, and the continued fear-baiting and arbitrary restrictions would be baseless. 

Surely, people deserve much more transparency from their government, especially as the state replaces medical doctors in diagnosing disease.

About Nick Murray

Nick Murray, of Cornish, currently serves as Policy Analyst with Maine Policy Institute, writing, researching, and bringing Mainers together over the issues facing the state. Previously, he served as Outreach Coordinator, planning events to spread the word about Maine Policy's work to new audiences around Maine.

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