Asymptomatic transmission

An expert on BBC news this morning was decrying the high false negative rate of “lateral flow” COVID tests, in the light of a study which re-tested negative asymptomatic students with PCR tests, and found half a dozen positives. This suggested that statistically 60 students in the group were in fact infected, rather than the three (if I remember rightly) revealed by the original test.

His conclusion that the lateral flow tests, being used by the government for screening against the manufacturers’ recommendations (as he rightly complained), will miss huge numbers of dangerously contagious people does indeed show a worryingly irrational, as well as massively expensive, testing policy. I pointed out last month that the former head of the UK screening service has poured scorn on the “Moonshot” testing programme, to no obvious effect. But the BBC’s expert then went on to talk about PCR as the “gold standard” test, and that needs to be severely challenged, at it has become a de facto assumption but is flat wrong. “Gold standard” has a specific definition in virology, and PCR testing does not, by any manner of means, meet it. TO CALL PCR A GOLD STANDARD TEST IS AN ABUSE OF SCIENCE, even if you are an expert on BBC news. Not that that will stop all our well-informed friends believing the lie and calling us Covidiots for doubting Auntie. Depressing, isn’t it?

At the very least, PCR is also being used for screening of asymptomatic people against not only the manufacturers’ recommendations, but the WHO, CDC and NHS guidelines up until this pandemic, when the advice suddenly changed. Readers will already be aware of the enormous concerns about false positives and cycle thresholds, which have still not been addressed. There ought by now to be an officially enforced cut-off of 30 or 32 amplification cycles on all PCR testing, if infectious cases are being sought, but there is not, as a letter (of which more anon) in the BMJ stated last week:

[T]here is no proper determination of an end-to-end operational false positive rate.

The powers and principalities can cancel Christmas for millions in just one day (after they send their parliamentary scrutineers home), but somehow they never get round to refining their basic laboratory practices, even a year on.

But aside from that, the truth is that the only true “gold standard” test is viral culture. And, as an editorial, also in the BMJ, pointed out just yesterday:

The only test for live virus is viral culture. PCR and lateral flow tests do not distinguish live virus. No test of infection or infectiousness is currently available for routine use. As things stand, a person who tests positive with any kind of test may or may not have an active infection with live virus, and may or may not be infectious.

The relations between viral load, viral shedding, infection, infectiousness, and duration of infectiousness are not well understood. In a recent systematic review, no study was able to culture live virus from symptomatic participants after the ninth day of illness, despite persistently high viral loads in quantitative PCR diagnostic tests. However, cycle threshold (Ct) values from PCR tests are not direct measures of viral load and are subject to error.

Note this well – there is currently NO WAY to know for sure whether an asymptomatic patient is carrying live virus, let alone being a risk to others. So the BBC expert’s problem might, indeed be, that many false positives are being missed by lateral flow tests. But it may alternatively be that huge numbers of false positives are being registered by equally unvalidated PCR tests. The only way to tell which is true is by using a gold-standard that is still not available after a year of global obsession with COVID. And that is what we call “following the science”: it means running after it at a distance and getting entirely lost.


Both types of test are being illegitimately used for mass-testing (and here’s the rub) because of an equally unvalidated assumption that asymptomatic spread of COVID-19 is a major factor in the pandemic. For the first time in history, asymptomatic people are being quarantined on the basis of dubious tests alone. Worse still, the whole country has been put into life-destroying restrictions on the same assumption, to the point that yesterday the dreadful Matt Hancock told the entire nation to act as if we have the disease. The UK is now the ultimate zombie movie, in which everyone – even oneself – might secretly be a zombie spreading zombiness, whatever that actually is… actually, it’s just a number on a test result.

That assumption explains all the social distancing, the compulsory masks, the closed pubs, the churches with seating like GCSE examination rooms, the empty supermarket shelves, the bankrupt businesses and all the rest. Before 2020, you put yourself into quarantine if you got the spots, the fever and so on, and maybe your family stayed way from granny in case they were incubating the bug as well. Now, the spectre of “asymptomatic spread” makes the whole world a collection of gloomy isolation wards.

But the letter I quoted above from the BMJ casts severe doubt on the whole question of asymptomatic spread. The concept arose from a bevy of papers from Communist China early in the pandemic, whose credibility is undermined by a new Chinese paper (cited in yesterday’s editorial, but equally suspect) which diametrically contradicts the others and dismisses asymptomatic spread. Both things cannot be true, and the contradiction makes the likelihood of propaganda rather than proper science very strong. One ought to exclude all these studies, or replicate them.

The BMJ letter describes how several meta-analyses of these early poor studies, with no regard to their methodological weaknesses, amplified the belief in asymptomatic spread by attaching it to prestigious western universities. And so the basis of our policy was, as it seems to be in most other respects, built on the sand of poor data that has come to be religious dogma.

But the BMJ letter describes how, in fact, the research literature shows that even pre-symptomatic spread, in which infected people transmit the disease before developing symptoms, is very rare:

To the extent that the latter phenomenon – which has in fact happened only very rarely – is deemed worthy of public health action, appropriate strategies to manage it (in the absence of significant asymptomatic transmission) would be entirely different and much less disruptive than those actually adopted.

But as for truly asymptomatic spread, the transmission of disease by those who never get ill – which is the basis of policies that have shut down the world economy and put us all into prisons both physical and mental – examination of the papers most often cited in its support, even disregarding their poor methodology, shows a total of such instances in the world literature of six case reports. That’s right, just six cases in the world, apparently transmitting COVID to a total of seven other individuals. And in any case all the diagnoses in these case reports were made using PCRs alone, with no regard to the possibility of false positives.

Now, neither BMJ piece examines the question of asymptomatic “super-spreaders,” those COVID carriers who, like Typhoid Mary, go on pub-crawls on the beaches of Sydney or the drizzle of London and consequently fill the hospitals with dying grannies. But a quick Google search doesn’t show much in the way of literature about this that doesn’t originate from mainland China or the popular press. I have a strong suspicion, given the literature examined by the BMJ authors, that their existence is more of an assumption than a finding from reliable data.

It is certainly politically useful – it gives the Territorial Support Group a public health reason for putting on their helmets and waving their truncheons whilst mobbing lone females demonstrating against lockdown. Arresting peaceful protestors, rather than violent extremists, was once a sign of state repression. But being a potential Typhoid Mary on the loose could be – and increasingly is being – interpreted as an act of violence by the police. It’s a bit like arresting witches in the seventeenth century, really, only with fixed penalty fines rather than even a biased jury trial. In this way, one is justified in removing even the right to protest against crap science informing putrid policy.

But I know what critics will say – I’m simply not paying attention to the experts at NERVTAG – or rather, the vocal minority amongst them that pushed the Tier 4 lockdown through. Ian Ferguson popped up again in that role. Instead I’m relying, once more, on those conspiracy theorists at that gutter-press rag, the British Medical Journal.

About Jon Garvey

Training in medicine (which was my career), social psychology and theology. Interests in most things, but especially the science-faith interface. The rest of my time, though, is spent writing, playing and recording music.
This entry was posted in Medicine, Politics and sociology, Science. Bookmark the permalink.

1 Response to Asymptomatic transmission

  1. Jon Garvey says:

    A reader has just made me aware of an excellent letter to Matt Hancock by Reform UK’s Richard Tice. A very informative read, with some research you may not be aware of: here.

    Who’d like to place a bet on whether we ever hear of a reply?

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