Not all ‘cases’ of Covid are created equal

It is a commonplace of science, medicine and everyday life that in order to solve

It is a commonplace of science, medicine and everyday life that in order to solve a problem you must first of all frame it correctly. If you ask the right questions, finding solutions can be straightforward. But if you ask the wrong ones you can grope in the dark forever. So having the right perspective really matters.

Unfortunately, the Government’s Covid approach has all the hallmarks of groping in the dark. In the name of “keeping everyone safe” we have endured local and national lockdowns, social distancing, masks, curfews, shutting cafés and pubs. Now we face further restrictions, based on naive modelling and virtually no evidence.

Our societal response doesn’t seem to have advanced much since 1665, the year of the Great Plague. Getting the framing wrong then cost many lives. If you believe (as people did) that plague is caused by corrupted air, not by a bacterium, you will take the wrong actions and make things worse. The authorities locked ill people in their homes with all who lived there, increasing overall mortality several-fold. Believing, paradoxically, that dogs and cats spread the plague, they arranged widespread culls, facilitating spread through a burgeoning rat population and their attendant fleas.

Funnily enough, Covid is actually carried on the air, so at least we have understood that bit correctly. But there has been a dangerous mission-creep since March. Then we were told a three-week lockdown was needed to stop the NHS being overwhelmed. But this has metamorphosed from the ugly caterpillar of protecting the NHS into the even uglier maggot of controlling case numbers. The wrong framing is that “case numbers” are being equated with “positive” tests.

What is a “case” of Covid? Let’s say you developed a viral cold last winter. Were you a “case” of a viral respiratory infection? On a theoretical level the answer must be yes. But on a practical, real-world level, the answer is no: you went to work and carried on with life. You were invisible to the authorities. Let’s say it got a bit worse and you saw your GP. Still no. You decided to take a couple of days off. Still no – you might show up in sick leave statistics, but not as a case of respiratory infection. If you got so far as being admitted to hospital with serious illness, you would show up as a “case” – a tiny proportion of those who actually had the illness.

The contrast with today is clear. Covid was made a notifiable disease in February, obliging all “cases” to be reported to the authorities. Since the only way to identify Covid is with a lab test, positive tests have been equated with positive “cases”. Back then, it was claimed there were no asymptomatic cases, but we now know that 90 per cent or more of people have Covid asymptomatically. A positive test is clearly not a positive “case”.

We also know that Covid affects different groups of people very differently: there is a thousand-fold difference in the severity of the disease between young and old. So the meaning of a positive test cannot be equated with its meaning in March, because the incidence of the disease at present has a completely different demographic.

Then there’s the issue of the tests themselves. Plausible false positive rates make up a substantial proportion of “positives” as unverified mass testing is rapidly rolled out. There is profound uncertainty around what low viral titres – found in a high proportion of young asymptomatic people – mean. Most probably very low infectivity. T-cell (as opposed to antibody) testing indicates that many people already have resistance to the virus. The more we know about this virus, the more it is like viruses we are already familiar with.

And yet, the Government is looking for an easy way out of the complex mass of restrictions they have devised; “control” the “cases” and wait for a vaccine to save the day. Unfortunately the former is a classic example of rubbish in, rubbish out, and the latter is unlikely to happen effectively, given previous attempts.

It’s time for the Government to start asking the right questions; framing things in the light of accumulating evidence, not unexamined preconceptions. On that basis, the course we should be taking is clear: asymptomatic spread is good. Advise and help the very elderly and those with serious illnesses to shield if they wish – but do not compel them, it’s their life, after all. And let everyone else get completely back to normal.

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