Only in Liverpool could it be done. Announced with a fanfare fit for a king, Liverpool has become the first city in the UK to organise mass covid super-spreader events, all in the name of public health. All covid symptom free Liverpudlians are being urged to gather at multiple sites across the city over the coming days in a pilot study to assess whether residents of the city famous for its identikit citizens really are thick enough to congregate in groups of a hundred or more to facilitate rapid covid spread across the community. Speaking to the BBC, Matt Ashton, the city’s Director of Public Health said, “This is a fantastic locally led national opportunity to get hundreds of uninfected people to mingle with infectious but asymptomatic super-spreaders, and spread covid far and wide, using rapid lateral flow infection. It’s not for nothing we say in Liverpool, you’ll never walk alone!”
Hashtag #LetsGetInfected may be bonkers, but so too is #LetsGetTested. Billed as a local pilot for Operation Moonshot, it offers rapid testing for covid to anyone who wants it. A dozen or so walk in centres have already been set up, with more to come, and thousands have turned up, citing in true Liverpudlian style a sense of civic duty for their altruistic behaviour. Soldiers from the Yorkshire Regiment, armed with nothing more lethal than swagger sticks and swabs, have marshalled the punters, and guided them through the tests. It all seems so well intentioned, and such a good idea — but nothing could be further from the truth.
Roll out has been a shambles. Arrival queues regularly ignored the rule of six, and included symptomatic and asymptomatic individuals. Perhaps #LetsGetInfected should be trending after all. Those taking the tests have struggled to get samples, given the body’s natural reluctance to have even a blunt stick rammed up the nose. But these are practical problems of implementation. The real problems lie at a deeper level, in the basis for and planning of mass testing. Depressingly, these major flaws are all well known — unless, it seems, you happen to be a Moonshot enthusiast, or someone employed in public health in Liverpool.
Although not entirely clear, it seems likely that all of the asymptomatic individuals will be tested using lateral flow rapid antigen tests, possibly with some also getting RT-PCR tests. Rapid antigen tests, as their name suggests, test for antigens rather than RNA, and are similar in process to pregnancy tests: you dab some fluid (in the SARS-CoV-2 test, an extract from a nasal/throat swab) on a strip, and a short while later the colour banding on the strip gives you your answer. The particular brand of test being used, purchased at 138,240,000USD (about £105m), is the Innova SARS-CoV-2 Antigen Rapid Qualitative Test. The test’s ‘Instructions for Use’, which include some background data, are available online, and they do not make for comfortable reading: the test is explicitly not suitable for mass screening of infection, let alone infectiousness. The instructions for Use note, for example [comments]:
“The SARS-CoV-2 Antigen Rapid Qualitative Test is … intended for the qualitative detection of nucleocapsid antigens from SARS-CoV-2 in human nasal swabs or throat swabs from individuals who are suspected of COVID-19 by their healthcare provider within the first five days of the onset of symptoms.” [tests for antigens, not live virus]
“Positive results indicate the presence of viral antigens, but clinical correlation with patient history and other diagnostic information is necessary to determine infection status.” [ditto, plus do not interpret without clinical information]
“Negative test results do not preclude infection and should not be used as the sole basis for treatment or other patient management decisions, including infection control decisions.” [infection control decisions include need for self-isolation]
“The performance of this test has not been evaluated for use in patients without signs and symptoms of respiratory infection and performance may differ in asymptomatic individuals.” [we have no idea whether it works in asymptomatic individuals]
“The kits for rapid detection of SARS-Cov-2 can detect both viable and non-viable SARS-CoV-2 material. [the familiar finding needle in a hay stack does not mean your haystack is a sewing machine]
“Read the results at 20~30 minutes. Strong positive results can be reported at 20 minutes, however, negative results must be reported after 30 minutes. If positive signal appears after 30 minutes, it should not be reported as positive.” [not the clearest of wordings, but you get the drift. Also, it is a very short time window – all to easy to lose track if you are running thousands of tests…]
And so on. Dr No could give more examples of why the test being used is unsuitable for use in mass screening, including of course the real world false negative (infections individuals given the green light to go out and spread the virus) and real world false positives (non-infected/infectious individuals ordered to self-isolate, along with their contacts, when they don’t need to), but the Instructions for Use, in the extracts above, make it clear the test is simply unsuitable for intended purpose.
Which makes it all the stranger that both Dr Susan Hopkins, PHE’s Test and Trace Director and Matt Ashton, Liverpool’s Director of Public Health, both believe the tests can detect not just infection, but infectiousness. A tweeted quote from Hopkins reads: “The tests we are using in Liverpool are accurate, especially in finding people who are infectious at that moment in time, and so are more likely to pass it on to others.” while Ashton got himself interviewed yesterday on WATO, saying (at around 29 minutes in): “The lateral flow testing is really exciting because it is a really good test of infectiousness, so it tells you with a high degree of certainty whether you are infectious or not.” Perhaps in their rush to roll out the mass screening pilot in Liverpool, they forgot to read the test’s Instructions for Use. Or perhaps they did — but crashed on regardless. After all it’s a pandemic, we’ve got to do something.