Failing the smell test

On September 25th, 2020

Besides a vaccine, the Holy Grail in the Covid crisis that every government has been reaching for has been the setting up of ‘test and trace’ schemes.

Testing and tracing have been credited with the lower incidence of Covid in places like Italy, when it used to be one of the worst-hit countries, Germany or even the Philippines.

But these kinds of schemes are reliant on widespread testing. So the $64,000 question is: how good are the tests?

Dr. Robert Verkerk, director of the Alliance for Natural Health, and a columnist on our magazine What Doctors Don’t Tell You, and his colleagues have addressed just this question. Recently they offered blow by blow dismantling of the accuracy of the Covid test.

This involves deconstruction a few types of statistical analysis, so I’ll try to relay Rob’s brilliant findings as simply as possible.

Currently, aside from the clinical symptoms (like loss of taste and smell) most cases of Covid are confirmed through use of the RT-PCR test. That alphabet soup stands for ‘reverse transcriptase polymerase chain reaction,’ which means that the test works by using an enzyme called reverse transcriptase to turn a piece of RNA into a matching set of DNA.

The PCR or ‘chain reaction’ portion then starts crazily replicating the DNA exponentially, with a fluorescent signal added to these DNA doppelgangers to easily identify them.

Kary Mullis, the offbeat inventor of the test, was awarded the Nobel prize for his discovery, which has been used to detect, among other things, disguised moose meat in hamburger, the brain of a 7000-year-old human mummy, the true identity of the outlaw Jesse James and even the fur of a cat named Snowball, which turned out to be crucial in identifying the perpetrator of a murder.

A highly sensitive test in the lab, no doubt, but by Mullis’ own admission, no good when it came to diagnosing disease out there in the real world.

Rob quotes the biochemist Dr. David Rasnick, who says that the PCR test is a ‘great scientific research tool,’ but a ‘horrible tool for clinical medicine.’

A bad test for Covid

Why could such as sensitive test be rubbish at detecting a virus? When attempting to work out the accuracy of a test like this, researchers use two yardsticks: a test’s sensitivity –its ability to detect true positives – and its specificity – its ability to detect true negatives.

So let’s say that a test has a sensitivity of 99 percent. That means that out of 100 tests, only one of the tests will pick up a false negative. As for its specificity, out of another 100 tests, only one of the tests will show a false positive.

And all the makers of the Covid PCR tests claim high specificity and sensitivity.

So far so good. Despite the fact that governments like to say we are in the midst of an epidemic of Covid, the fact is that a very small percentage of us have this virus at any particular time.

So in that situation, says Rob, scientists have to rely on a statistical method called ‘Bayesian probability theory’ which says that if we know the ‘disease prevalence’ – ie, the proportion of the population in any community, state or country who are infected with the virus – we can better assess how accurate the test result is.

Here’s where it gets interesting. The lower the prevalence of the Covid virus, the wildly less accurate the test becomes in accurately identifying a true positive. The opposite is the case with false negatives; the higher the prevalence of disease, the wildly less accurate the true negative test results.

To assess the accuracy of any given test result, says Rob, you also need another statistic. This one makes use of Baysian probability to work out the Positive Predictive Value (PPV) and the Negative Predictive Value (NPV), both used by the late Doug Altman, a professor of Statistics at Oxford University, to determine the accuracy of diagnostic and screening tests.

Assuming that the tests have a 95 percent accuracy in sensitivity and specificity – which most companies producing these tests claim – just watch what happens to the PPV – the chance you get an accurate positive reading –  when the percentage of the population with Covid falls.

These are Verkerk’s calculations (he is a PhD from Imperial College, essentially one of the world’s premier universities in mathematics and science, so he knows his onions) for parts of the UK.

For the Northwest, where 0.21 percent of the population supposedly have Covid, representing the highest prevalence of the virus, the chances of an accurate positive test stand at 9 percent. In the West Midlands, the area with only 0.04 percent of the population infected, the chances you are going to get an accurate test is essentially 1 percent.

What about the US, the country with the world’s highest number of cases, which reported 302,715 cases in the last seven days as of this writing?

That is, essentially 1 in every 1057 Americans, or a prevalence of 0.09 percent. According to Verkerk’s statistics, that means that the accuracy of those positive tests is, at best, about 15 percent.

You can calculate this yourself, says Rob, by plugging in the numbers in Medcalc, which is statistical software for non-scientists:

Why is this so? Verkerk describes it as analogous as looking for a needle in a haystack.  “As real needles are so few and far between, the chance of finding things that look like needles but aren’t increases.”



7 responses to “Failing the smell test”

  1. Tom says:

    Great analysis and I fully agree about the money part. It's not the $64,000's the $640 billion dollar question when talking about vaccinating the world. My points: I have heard that 80-90% of the world's population has already has some exposure to a coronavirus ( not particularly this one). Partial immunity perhaps? Why have there not been thousands of autopsies performed over the last 6 months? I hear that only a handful have been allowed. No vaccine has ever been created for any coronavirus and certainly no vaccine in under 5 years except for the mumps in the late 1960's. Can we trust a vaccine made in less than a year? I am hearing that vaccines will often expose people to other viruses or such other than what the intended protection was for. According to the CDC chart on their web site, over the last 10 years they estimate that the flu vaccine has only been effective less than half the time. Why would this "miracle" vaccine be any different? Experimental RNA altering vaccines? No thanks. The root of most medical evil is BIG PHARMA!

  2. Tom Carroll says:

    Lynne, thanks another great article. The odd, oh-so unfortunate thing about it, is that no matter how much information is brought forward, those without ears to hear; continue deaf'tly on their way.

  3. Kerry D Kidman says:

    What is implication that you wish readers to take away from this post? You rely on Dr. David Rasnick, known to be bogus. According to Wikipedia: "Rasnick was a prominent member of the AIDS-denialist movement, which claimed that HIV either did not exist, or did not cause AIDS. He claimed that HIV was a harmless "passenger virus" incapable of causing any disease.[5] In association with Matthias Rath, Rasnick traveled to South Africa, a country with one of the highest incidences of HIV/AIDS in the world, where they discouraged HIV-infected individuals from using antiretroviral drugs and instead promoted the use of proprietary vitamin mixes which were claimed to fight AIDS. Rasnick also advocated a complete ban on HIV testing in South Africa, and denied that there was "any evidence" of an HIV epidemic in South Africa.[5] In 2008, a South African court ruled that the trials conducted by Rath and Rasnick were illegal, and barred them from conducting clinical trials or advertising vitamin supplements in the country.[2][6][7]" Why would you rely on such a person? Why do governments and people all over the world, with vastly different ideologies and backgrounds use and rely on this test? Are they all stupid or worse?

  4. Peter Vos says:

    Excellent. So, why have governments decided for a lockdown or why didn't they adjust their false assessment?

  5. Robert Parr says:

    Fact no. 1 The world is overpopulated.
    Fact no. 2 The earth's resources are running out.
    Fact no. 3 One percent of the world's population own ninety percent of the wealth + and rising )
    Those rich 1% have to preserve what's left for themselves people. I'm sorry but we're all very expendable!

  6. Lisa Browne says:

    When I was coming back from Cairo and flew out of Dubai I was scanned by a device that would let the passengers board. Why isn’t this type of technology being touted or used? There were no swabs or close interaction just an infrared scan of the body as you walked by.

    Thank you.

  7. Patti says:

    Thank you Lynne. I’d read about Mr. Mullins earlier on in this crazy situation.
    Scientists research makes sense.
    I do know that a friend in Texas lost his mother to many complications she had previously to this. Cause of Death on death certificate was Covid 19. The daughter-in-law returned to hospital with queries & was insistent COD was changed. They reluctantly obliged. She found out that they would lose the money for changing the COD. They get paid for every Covid death certification. Hmmmm. Also here in Alberta a friend works as a nurse at a major city hospital. They had their first case approximately a month ago. Patient sent home as no life threatening issues. Some nurses & Dr.’s are wondering about this. My heart goes out to anyone who has lost anyone to this, or has long lasting health condition because of it. Just doesn’t seem right. I do agree that there are many more deaths to other diseases & drug overdoses & nobody’s making a stink about these at all. Blessings of God’s/creators love to all.

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