Mass PCR Testing an Expensive Blunder

Dr Tom Jefferson has a terrific piece in today’s Mail on Sunday, based on research recently published in Clinical Infectious Diseases (Oxford University Press), on the mania for mass testing.

For the past few weeks I have received a stream of unsettling letters and emails from members of the public. They are all complete strangers, people I’ve never met. They decided to get in touch out of what I can only describe as desperation.

They are at their wits’ end because they are testing positive for COVID-19 despite having recovered from their symptoms. Some never had symptoms in the first place but are still being told they have the virus long after any possible infection. They are anxious and confused. Their lives are on hold.

One family tells me how their mother caught COVID-19 in hospital in October but continues to test positive. “This is starting to cause problems with her receiving treatment for cancer,” they write, “so we’re trying to prove she’s not still infectious.” Another man complains of losing his sense of smell two months ago, his only symptom. Yet his test results continue to be positive. When will he eventually be negative, he wants to know.

After detailing some of the failings in the way the test is used, and the critical fact that the this simple yes/no test cannot tell us if the individual is still sick, or capable of infecting others, he writes:

Last Friday, however, an academic journal reported that almost a quarter (24%) of infected staff and patients at the John Radcliffe Hospital in Oxford were still testing positive for COVID-19 a full six weeks after the start of an illness that normally runs its course within 14 days.

If that were in any way representative, I’d have to conclude that the official coronavirus figures have been grossly overstated, with all the damage that entails.

As Newcastle University’s Professor Allyson Pollock said recently, the PCR tests were never designed to be used across entire populations. The manufacturer’s instructions, she says, make it clear that they are no more than a tool to help with diagnosis and they are “not to be used on healthy people with no symptoms”.

I believe that Britain’s new-found testing mania is a retreat from properly conducted clinical medicine as well as from common sense. And that we are witnessing a triumph of herd thinking, an expensive one at that. Most PCR kits still cost more than £100 to obtain privately, for example, and the Government says it is now delivering 500,000 a day. But even these figures are dwarfed by the £100 billion the Prime Minister is prepared to spend on a “moonshot” dream of supplying the population with tests more or less on demand.

All precision has been sacrificed and instead we are blundering through, imprisoning people in their homes, further crippling the economy long after the infection has vanished. This is why we must treat the Government’s daily tally of cases, often in five figures, with a huge dose of salt. And why we must restrict the reporting of positive coronavirus diagnoses to those who are infectious to others. These are the people who matter in a pandemic.

Perhaps in recognition, at least in part, of the of the unreliability of the PCR test, the Government’s emphasis is switching to the lateral flow test. Sky News reports that from Monday 1.6 million of these tests, which use similar technology to the pregnancy test and have a quicker turnaround, will be deployed in over 100 local authority areas. A reader wrote in yesterday, with this to say:

I am an NHS registered nurse and my hospital trust is now strongly encouraging twice weekly lateral flow tests for all its frontline staff (which I have politely declined). Interesting though how they use lateral flow tests for health carers (which has a low false positive rate) but continue to use PCR for the public (which has a high false positive rate). Its a win win for the government – less health workers requiring to isolate, whilst still maintaining a case-demic that justifies Tier 3 restrictions. Clever.

It is well known that the PCR generates high numbers of false positives (low specificity) due to high cycle thresholds. The Government is very tight lipped about what cycle thresholds are used, although cycles of 35-40 have been stated in the literature which likely only pick up old viral fragments. Surprisingly, even the fear mongering Anthony Fauci admitted that cycles this high would only pick up “dead nucleotides”.

I suspect that there might be a gradual move towards LFT testing in place of PCR, sold to the public for reasons of finance, speed (results within 30 minutes), convenience and accuracy. Maybe the change over to lateral flow testing will be one of the mechanisms to shift the narrative once the vaccines are rolled out over the coming months (read David Mackie article “How Will the Fiction be Sustained?“). Mass vaccination followed by a gradual switch from PCR to LFT (with its low false-positive rate) seems to be a plausible strategy that Boris will use to get out the hole he has dug himself. The question is, will the public notice the sleight of hand?

Stop Press: The University of Surrey and the National Measurement Laboratory have published an article in Clinical Chemistry on laboratory contamination, a key cause of PCR false positives. There is a good summary available here.