The recent brisk treatment of Professor Allyson Pollock on twitter by fellow medics reminds us of how polarised views about covid–19 have become. Pollock’s chief point, that a positive PCR test for covid RNA doesn’t on its own prove infectiousness is perfectly reasonable, and Dr No agrees. Finding a broken fragment of a needle in a haystack doesn’t mean you can conclude the haystack is a working sewing machine. Yet an army of contrarians queued up, expressing views ranging from astonishment that she ‘would be willing to risk lives like this’ (argumentum ad homicide), and admonition ‘we have been screening pre-op cases for six months – it’s the accepted standard of care…the position of all four surgical colleges is clear’ (argumentum ad authority and populum), through incredulity ‘the whole thread is wrongheaded’ (argumentum ad bonehead) to imploration ‘loved your book but you are absolutely supporting some nonsense here’ (absolutely argumentum ad incredulum). There was, in short, argumentum ad nauseam, but what was conspicuous by its absence was even a single reference to any evidence that a bald positive covid PCR test confirms infectiousness.

One of the most potent core beliefs of the covid activists — those who want to see more done on a grand scale to control the virus — is that, one way or another, we can manage our way out of covid. Whether the action is sharper and harder lockdowns, or bigger and better mandatory masks, or more frequent and wider ranging testing, the core belief is the same: it is by concerted managed effort that we will control the virus. Dr No, ever the sceptic, has his doubts. Might it be that while all this action makes the activists feel better in themselves, the stark reality is that they are blind hamsters running ever faster in their wheels, oblivious to the fact that however hard or fast they run, they will never get anywhere? Could it simply be that there is no grand scale managed solution to covid, and the pretence that there is lies somewhere between foolish folly and reckless hubris?

Along with social distancing, which includes that commedia dell’malarkey that is masking, given a mask is a barrier, covid–19 testing is one of the three bendy prongs of our rubber trident against SARS-CoV-2. The third is immunity, howsoever gained, which may yet turn out to be the only prong with a real tip. Testing, the way it’s supposed to be, serves three aims. The first, where n = 1, is to make a diagnosis in an individual patient. The second, where n = up to a few dozen, is to identify cases, for contact tracing. The third, where n = up to 67 million or so, is to carry out mass screening, or surveillance. It is hugely expensive, and may, as we shall see, come to be the most expensive covid–19 monetary cost of all, and yet, on the face of it, covid–19 testing is a broken arrow. How shall we count the failures? Let us see.

There is a priapic triumphalism emergent among the mask-wearing, virus-suppressing, lockdown-touting cognoscenti. As the weather cools down, the war on heresy is hotting up. The Lady with the Blow Lamp is now the Lady with Two Blow Lamps, one in each hand, trained not just on straw men, but also on Dr No and other doctor-outliers, covid-deniers and mask-decriers. One over-heated academic cum hack got so fired up that he dubbed the whole Sikora-Heneghan-Gupta letter writing cabal as a ‘group of fringe scientists, Conservative lobbyists, paid Republican trolls, and’ — for good measure — ‘a COVID-19 death toll falsifier’. Cripes. The less frantic  and more restrained whose cups nonetheless overfloweth sing out their alarms with a refined air of self-importance straining their bastions, like the fat lady whose corset is starting to crack open at the seams. But in their rush to certainty, they have forgotten that there is no fool so great a fool as an all-knowing fool, for only such a fool can possibly be sure that they know all there is to know about covid–19.

The recent odious twitter spat between the self-appointed witchfinder Dr Dominic Pimenta and the aggressive broadcaster Julia Hartley-Brewer about covid false positive rates triggered by Hatt Mancock’s assertion that the rate was ‘less than 1%’ has yet again highlighted the rampant confusion that continues to plague the meaning and interpretation of screening and diagnostic tests. Dr No understands this confusion only too well, since he has struggled for many a long hour to get his head round what the test results and their derivatives — the sensitivity and specificity, positive and negative predictive value etc — really mean. So, in the interests of clearing his own head, and, he hopes, helping a few readers to clear their heads, Dr No is going to do a run through on tests, and explain what matters, and why it matters. Inevitably it is a long post, but at the end we do at least have something of a possible, but baffling, answer to the Pimenta Hartley-Brewer spat.

This remarkable photo, apparently first published by The Spectator, begs a thousand captions, none of them polite. In the interests of least offence, Dr No suggests, ‘When I say jump, you jump!’, but really it almost works better without a caption, because it is the expression on the faces, and the fist about to thump the table, that tell the story. Cummings looks as if he has just been shot in the back with a poison dart, and is about to fall face down on the table, Boris looks like a truculent schoolboy, up before the head after being caught having yet another dump in the College rose garden (‘I couldn’t help it, sir, I had to go’), and Mancock looks like the truculent schoolboy’s hanger-on, who knows he too will get flogged, on a charge of common purpose. Or maybe he’s wondering whether the head knows about the spliff he had behind the College bike shed. But whatever the words and thoughts at play as the photo was taken, surely the most remarkable thing is the insight we gain of the disarray at the heart of government.

Listening to the Prime Minister’s speeches on the radio, one hears irregular thuds in the background, as if a workman in a distant room was testing the heft of a sledgehammer. The thuds are in fact the Prime Minister thumping the desk, dispatch box, or lectern, a displacement activity occasioned by his spectacular inability to hit a single covid nail on the head, let alone whack even a solitary virus. One fears the thuds will become louder and more frequent as time goes by, and start to drown out the words, until one day all speeches come to be the cacophony of a multitude of workmen beating a devil’s tattoos with their hammers as they demolish the stony guardians of ancient British liberties one by one, until we become, as Mainwaring almost said, a nation of automatons led by a lunatic who looks like a clown.

Proof, were proof needed, that many of the pillar 2 community covid-19 tests done recently were carried out on asymptomatic people came yesterday morning from Absolutely Mancock. Absolutely doing the morning’s media interview round, he confirmed that as many as a quarter of the tests were done on people who absolutely were not eligible because they absolutely did not have either symptoms, or what he sinisterly called a direction from an official, to have a test. The rest of us have absolutely known about this problem for a while (in Dr No’s case, for weeks, if not months), and the problem it causes, which is once again to pour mud on the question of when is a case not a case. True false positives (positive result when no viral fragments are present) aside, much of the problem has to do with fact that the PCR (swab, antigen) test checks not for the presence of disease, or even entire infectious virus, but instead looks for tiny fragments of genetic material from the virus.