Dio wrote:I find it very odd. Given how infectious this seems to be, it baffles me that contact tracing without lockdown works at all.
But yet South Korea did exactly that.
Because they jumped on it pro-actively from the very first case and went hard on "test, trace, isolate", while the numbers were small, to keep those numbers small. Going hard to stop it getting a foothold in the population in the first place.
And the numbers speak for themselves, as they've had, at time of writing, only 229 deaths total and just over 10K total cases. For a country with a population of around 50 million, which is perfectly comparable to the UK's 60-ish million.
And, as tufty rightly notes, the "test, trace, isolate" doesn't have to be perfect - indeed, as you note, it essentially cannot be perfect, as that's really a practical impossibility - but as long as it brings the infection rates right down, then it can be good enough.
Basically, the rough estimate on the wild spread rate for this thing, from all the world data so far, is about 1.3 which roughly means that, in the fortnight you've got this for, you're infecting about 3 other people on average.
Yeah, looking at the numbers, you might think that this virus is more infectious than that. That, like, that hypothetical person landing in Heathrow is instantly spreading it to 100+ people. But, actually, no, on average, it's about 3 people.
The problem is the exponential growth. Those 3 people, on average, infect 3 others. So that's 9 people and they infect 3 people on average, so now we're at 27 people. Then those 27 infect another 3 each and we're at 81 people.
You get the gist. The formula is roughly 3^x and it's the
exponent that's increasing here, so that's why it balloons to big numbers so fast.
It's not because there's one guy out there single-handedly infecting 100+ people within a few hours. The problem is that it's exponential: 1, 3, 9, 27, 81, 243, 729, 2187, 6561, etc. and folks can be wandering around asymptomatically for up to two weeks, so we don't realise that the "virus bomb" went off there until a fortnight later.
But this is where the "test, trace, isolate" thing comes in. The long incubation period, which is a bad thing for spread, is now flipped to being quite a useful thing for contact tracing.
That guy who jumped off a plane. He gets sick a week later. He's brought to hospital and tested. Okay, we have a positive. Where did you go and who did you meet? Bring those people in and test them. If they're negative then there's no branch there (so no further contact tracing needed). If any of these people are positive, then ask them where they went and who did they meet. Bring those people in and test them. Rinse and repeat. Go down all the positive branches to find more positives, until there are no more branches to follow.
And here's the thing. To infect all those people, it could have taken the virus many weeks, but you can rush down the branches and pick these people up in days. And you're hopefully catching them early - they're still asymptomatic and might not know they've got it - to cut off the spread before it happens.
If you wait for symptoms before testing, then you're already two weeks and three people behind the curve. With "test, trace and isolate", then you can get ahead of it.
And the thing is, if you can reduce the infection rate from 1.3 to 1.0 then something magical happens in the maths. The formula is then "1^x" and, well, one to the power of anything remains one. It's no longer increasing. So reducing the average spread from 3 people to 1 person - be that by lockdown or contact tracing - halts the increase. Get it below one and it'll peter out of its own accord.
But, as the WHO's Director General put it: “Not testing alone. Not contact tracing alone. Not quarantine alone. Not social distancing alone. Do it all”.
And though no-one was listening to the WHO, that was exactly right. Imagine the country that had actually followed this, with German levels of testing, South Korean levels of contact tracing, AND had all the lockdown stuff in place as well - and had got all these things up and running early while there was, say, only a few dozen cases in the country. That hypothetical country - that, unfortunately, no-one in the world actually fits - would have killed this off and barely been scratched by it.
The WHO isn't a perfect organisation by any means. Indeed, there is, of course, no such thing.
But they issued the worldwide alerts in January and they were advising all these measures from the off. And, come on, look at that quote above and the famous "testing, testing, testing" - they were not mincing their words or being at all vague about things here. It's just that countries, all over the world, ignored them.
They thought "ah, this is just like the flu" and started coming up with insane "herd immunity" plans, and were loathe to shut down parts of the economy "unnecessarily" (except, of course, events since have absolutely 100% proved just how bloody necessary it was to have done that back then - because they didn't, and that's, in fact, shaft the entire world economy massively more for their delay). And they're still - such as Trump - rather insanely insistent on re-opening the economy again, when they're nowhere near having this problem under control (America has about 30K cases a day right now).
I was saying this from the off. As this is exponential growth, then you have to jump in early. You have to get in fast, before it gets a foothold. Not dither and delay for a week, not bothering to ban mass gatherings or close schools, after already wasting a week talking about "herd immunity" which is an insane non-plan.
And this is what South Korea also neatly demonstrates: If you're in there straight away, no delay, to start testing, tracing and isolating from the first cases, then you can actually get this under control, without national lockdowns and shutting down most of your economy. If you attack an exponential, while it's still down in the low numbers, then you can prevent it ever getting to the big numbers in the first place.
Seriously, if all these nations had started moving just a week or two earlier, then the numbers would have been logarithmically less. Like South Korea's.
And the idea that it couldn't be done is smashed by Germany. They did it. They listened to the WHO advice and got their testing regime up to strength and you can see the difference in the numbers. More impressive, but their mostly land-locked geography in the centre of Europe would actually be working against them.
Unlike, you know, a more naturally-defended island, who could have cut off transmission almost totally, by grounding planes and not letting ships dock (or, you know, do the "2 weeks quarantine" thing - you can travel in and out, but you've got to sit in quarantine for 2 weeks, to be sure you've not got it and can't pass it onto anyone). And then waited for things to die down, before releasing the brakes gradually. Which would have been a touch of self-inflicted economic harm, true, but as absolutely nothing compared to what we have now, which has felled the entire economy for months and put us in massive debt for a generation. Bailing out Richard Branson for a few weeks of inconvenience would have been absolutely sod all in comparison to that.
The dither and delay to start dealing with this was economically, socially and morally unacceptable. The WHO issued their worldwide alerts in January. There was enough time, but there was simply zero political will.
"Words ought to be a little wild - for they are assaults of thought on the unthinking."
- John Maynard Keynes
