When the U.K. government was confronted with COVID-19, it made the preliminary decision to respond by putting the elderly in tight social isolation while the virus spread among the less vulnerable general public and created herd immunity. This already looks like a disaster that delayed social shutdown measures at exactly the wrong moment. More serious scientists appeared with models showing that a let er rip strategy would lead to the disaster like the one that has materialized in Italy a country with an old population in which it is usual for the young to be domiciled with older relatives far into working age.

The models that led Britain astray briefly were predicated on a stupid error: the coronavirus was treated as having flu-like characteristics. This led the government to underestimate the immediate pressure that COVID-19 would place on hospitals if allowed to circulate freely. The world, or the part threatened by the virus, has switched to extreme social shutdown measures in an effort to lock the virus out to deny it local toeholds by reducing its effective reproduction rate below 1.0.

You know most or all of this. In the last few weeks Ive written several times that I dont know what the immediate future will look like. But I am forming a guess.

Immediate harsh social shutdowns are meant to buy time. If they work very well, we could achieve what the Chinese claim to have done in Wuhan province, ground zero for the disease. The trick, epidemiologically, is to get everybody out of the infected category, breaking the link between the susceptible crowd, which hasnt been exposed, and the recovered group, which enjoys immunity of some uncertain duration. If we can reach and maintain that state for long enough, the virus will have no local human hosts left.

COVID-19 thus goes locally extinct, and even the susceptible are safe until the immunity of those who have recovered starts evaporating, or the virus mutates. Those are problems for a future we would have time to avoid by manufacturing fast tests, treatment drugs and a vaccine.

If we cant suppress the virus, for economic or biological reasons, we are back to an unchosen let er rip strategy. Eventually we will get herd immunity. The British werent wrong about that part. With each person who recovers or dies, the viruses lurking in the infected population have fewer chances to propagate, and the community reproduction rate slows.

The herd immunity threshold, which would come to something like two-thirds of the population for this virus, is the point at which the reproduction rate is just zero: there are no targets left. But we would start benefiting before we reach that precise point. Past a peak of new cases, the reproduction rate, which is at its largest when nobody is immune, begins to shrink as the virus itself shunts more people into the recovered/dead bin.

It seems obvious that our most important goal is to avoid becoming Italy. When hospitals reach their capacity to handle COVID-19 sufferers in extreme respiratory distress, the mortality rate explodes. At the same time, it may not be practical for us to keep everyone locked up at home for six months. If we had very good data about who is at great risk from COVID-19, and who is likely to be able to walk it off like a cold, it might turn out that we are able to release the naturally strong from confinement now, or very soon.

Theyd spread the virus amongst themselves while the weak stayed indoors. Some would get sick this is a plan for voluminous death, but with functioning hospitals. If our data was good enough, we could free only enough people to keep intensive care units from filling. We would go slowly, painfully slowly, perhaps choosing age groups to leave social isolation a few people at a time.

Isnt that just the stupid British strategy? Yes but based on evidence, which should be obtainable, instead of nonsense. We dont know that the shutdown strategy we are pursuing will work, or be tolerable. I have hope for the shutdown, and I see other possible escapes from this predicament, along with untried approaches like Asian-style social mask use. But I havent seen anybody (apart from Dr. David Katz in Fridays New York Times) talk about the possibility of a modified British strategy an intentional, organized, careful creep toward herd immunity.

The British strategy was stupid mostly because the underlying numbers were stupid, and because total suppression of the virus was a much better thing to try first. I dont doubt this. I would plead with every reader to practice social isolation.

And even a modified British approach may not be possible. We are seeing, in an anecdotal way, some badly afflicted people with no prior comorbidities. But all the information Ive seen still suggests that COVID-19 preys with particular savagery on the old, the diabetic, those with heart disease and the hypertensive (possibly because of their medications). With enough data about this we might be able to develop a points system or a colour code. Compromised reds stay indoors, maybe for a good long time, while greens get on with life and economic production.

My brain bursts without blood pressure medication, so Im probably a red. I could stay in for a year (and work) if theres a functioning outside world, but its already functioning poorly enough to make isolation less convenient. The next fortnight or so will show us whether were headed to where we want to go: toward Wuhan. If not, I expect our public health officials and politicians to consider, and begin hinting at, a change of destination.

National Post

Twitter.com/colbycosh

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Colby Cosh: How the British got their COVID-19 strategy so wrong (but might still be right) - National Post