On Speculating About A Lock Down Period

[danieldwilliam]

My guess is that we'll be in some form of close national quarantine for 8 weeks.

I think this for two reasons.

One, my experience as a parent tells me that if you have a time in mind for an unpleasant wait for your child of X time when asked you tell them "we will talk about it again in X/2 time" on the grounds that they will accept that they can wait x/2 time and then when asked to wait again will kno that they can wait x/2 time. What I think will happen is we will do 3 weeks, then be told we need to another 3 weeks and at the end of those 3 weeks have a 3 week phased stand-down from close control to less close control.

Two, some Fermi estimating. The virus seems to have about a 2-3 period when it is infectious. People seem to be most infectious for a week before they show symptoms, then a week whilst they are symptomatic. Then less infectious, and also less mobile as they are ill.

The aim of the game is to reduce the onward transmission rate from about 3 to below 1.

So, in 2-3 weeks time, everyone one who has the virus will be symptomatic and will have passed it on to everyone they can pass it on to. Which, if we are all closely quarantined will just be people in their own household. (We will still get onward transmission from contact during "essential work" and exercise and so on). Then another 2-3 week period will mean that anyone who caught the virus from someone who only caught it on Monday will be passed the period when they, themselves are most infectious. Most of those households will then shift to self-isolating rather than being pre-emptively restricted. Another 2-3 week period gives you another lap of containing people who have the virus

So over a 8 week period we have between three 2-3 week rounds of infection and almost everyone in a household that has the virus in it will have either had it, or be having it but passed the most infectious period, or be having it and be in bed obviously ill.

If we are very lucky then we might reduce the number of undetected carriers to double digits over that six week period.

Then I think we see some restrictions lifted. A pick up in the number of infections for about 8 weeks followed by a second round of 8 weeks of close confinement ending about mid- September.

That's my guess, for what it's worth.

Comments

[cmcmck]

So when do we start asking: 'are we there yet?' ?

[danieldwilliam]

That depends on your parental nagging strategy - are you mounting a low-intensity long duration campaign, hit and run, or a major offensive to break the defensive capability of the driver?

[alithea]

Given I'm hoping to still be able to go on my mid September holiday to the West coast your prediction for a second round of confinement is not filling me with joy, although it does indeed sound perfectly plausible when you reason it out.

[danieldwilliam]

I think until a vaccine is approved for us (which I believe is a minimum of a year away) we're looking at series of more or less strict quarantine periods.

Unless the current UK government strategy is to attempt to irradicate coronavirus on the Great British mainland. In which case we're indoors for months until they have the resources to mount a track and trace programme for the whole country.

[miss_s_b]

That all makes sense

[danieldwilliam]

I am 100% confident it will turn out to be wrong. And wrong in interesting ways I hadn't even considered but the exercise has helped me get a sense of the likely dimensions.

[mountainkiss]

I think it might be longer. There is a massive political impact of being under less quarantine than other countries and then having more deaths, even if the two aren't actually appearing to be correlated. (It's not at all clear that lockdown in Europe is reducing deaths, at the moment.)

[danieldwilliam]

You are right. One should not forget the political angle in all of this. I think anything that is not demonstrated by science to be actively harmful but is populist might happen. Which might include much longer periods of quarantine.

Johnson is, after all, a populist and populists are often driven by the person who *thinks* they ought to be driving the Clapham omnibus.

What are you seeing that suggests to you that quarantine in Europe is not reducing deaths?

[mountainkiss]

https://www.itv.com/news/2020-03-24/disappointment-as-evidence-coronavirus-lockdown-is-working-in-europe-fails-to-prevail/

[danieldwilliam]

I would not read too much in to one day's statistics.

And I'm personally very sceptical about the business model of journalists at the moment. They make more money selling bad news and outrage than otherwise. So, I'm inclined to look at a story about one bad day and think that it is the interests of the news vendors to make that a bigger story than it really is.

We'll know more in a week.

[mountainkiss]

I am sure you are right about that, but I've also been looking for a while for stats suggesting rates are falling as a result of lockdown and not seeing any. Italy went into lockdown on 9 March so they've had most of your 2-3 weeks and it's not so far had an impact.

[danieldwilliam]

I think we have to wait for the full 3 week period. Lots of people will have been carrying the virus on the 8th of March who only got sick on the 15th and perhaps only passed it on the week after the 8th.

I don't want to be Polyannaish about this but I do think it's a week too soon to tell.

If by the 1st of April Italy isn't seeing a distinct leveling off in new cases and deaths then I'll start to worry (more).

[mountainkiss]

In that case I don't think the maths works any more for your eight weeks.

[danieldwilliam]

How so?

[mountainkiss]

Because you're assuming the max asymptomatic period as constant rather than variable within the range to that point.

[danieldwilliam]

Yeah, yeah, I see that.

I think it balances out in practice with a) people who become symptomatic more quickly and b) people who isolate (rather than being quarantined) once they are symptomatic.

I'll mull it over and see if a change in assumptions makes a big difference to the 8 week period.