This is an interesting response by @cjsnowdon to @toadmeister but many of the examples he cites do not support his argument that infections start falling after lockdowns.

Here’s a closer look at 3 of them: France (31st Oct), Ireland (24th-31st Dec) & England (5th Nov)
1. France: 7-day cases were falling from 3rd Nov (not the 8th as @cjsnowdon states), positivity from 2nd, hospitalisations from the 5th. Given lag, these all show infections falling well before 31st October ...
France's estimated R-rate started falling from 24 Oct & there is no indication lockdown accelerated the decrease.

The 31st October French lockdown is not a good example of lockdown effectiveness.
2. Ireland: although full lockdown came in on 31 Dec, the lockdown measures were rolled out from 24 Dec so we might expect to see an effect on cases starting to show from early Jan, hospitalisations from about 5th Jan, deaths from mid-Jan …
Case data in Ireland are complicated by 9,000 earlier cases being reported in early Jan. So we just don’t know if “Case numbers peaked on 8 January” and we probably need to rely on admissions & death data.…
Admissions peak on 20 Jan. A lag of 10-12 days indicates infections peaked 8-10 Jan, long after even full lockdown on 31 Jan. You might argue admissions stabilised earlier than the 20th which would be a better fit, but even today, hard to see a strong trend down.
Deaths are even less hopeful for the lockdown case. Even now, 6 weeks after lockdown measures started to be rolled out, there is no clear downward trend in deaths.
Anyone know if Ireland has data on cases by test date &/or deaths by date-of-occurrence? Perhaps that would give a different picture but on the face of it, Ireland does not look like a great example of lockdown effectiveness.
3. England November: National positive case data does fit with a LD effect but Zoe estimates suggest peak pre-lockdown. Also, big regional differences complicate things with infections clearly peaking in some regions pre-lockdown ...
Further, infections in London, SE etc. started rising again *during* lockdown (I know: "new variant") but even worse ...
… when you look at deaths & admissions data both nationally and by region, there is pretty much no sign of any benefit of LD at all & little sign that releasing LD made things worse.

November in England is not a good example of lockdown effectiveness.
Sometimes a fall in cases fits in with lockdown timing, very often it does not. It is possible LDs have some marginal benefit but the evidence for them is just very weak.

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More from @cricketwyvern

4 Feb
A self-proclaimed fact checking website run by a Conservative MP & Govt policy advisor still states “Cases were not falling before the January 2021 lockdown”. They refer to 3 pieces of evidence ...
... 1. Weekly positive test data:

Weekly data obscures the daily peak but even so, PHE surveillance show peak was in wk 53 (28 Dec-3 Jan), i.e. pre-national lockdown, consistent with the daily data.…
2. "ONS infection survey ... rose to 1 in 50 by Jan 2 2021":

they don’t clarify this is prevalence (total currently infected) which will peak much later than incidence (new infections). As it happens, ONS daily estimates suggest even prevalence peaked pre-lockdown.
Read 6 tweets
31 Jan
Two things annoy me a little in the school debate. First, well-intentioned comments like "schools should be last to close & first to open".

We never debate when supermarkets should close. It is just accepted that they are essential & must stay open. So it should be with schools.
Second is the suggestion that there should be a trade off: if schools stay open something else has to close.

That reasoning assumes schools being open plays a significant role in infection spread. In fact, the evidence for that is, at best, weak. e.g.:
Read 8 tweets
21 Jan
In his recent article, @cjsnowdon claims that England's November lockdown was a good example of lockdown effectiveness. Let’s look at that claim using the ONS death-by-date registration data which have now been updated for the relevant period.
Although there is some uncertainty over the average lag between infections and death, we should expect any effect of lockdown to be visible in the deaths series after about three weeks.
If the 5th November lockdown had been effective, we might expect a beneficial effect on the deaths trend from about 26 Nov and an adverse effect from about 23 Dec, reflecting the relaxation on 2 Dec.

So what actually happened?
Read 10 tweets
19 Jan
Update to Sweden.

Now Christmas testing/reporting effects have worked through, we can see a decrease in positive tests of > 40% since peak just before Christmas.

ICUs also coming down steadily. We can expect deaths to follow though backdating means it is hard to be sure yet. ImageImageImage
Sweden has introduced some more measures over recent months, though nothing like those seen in UK & elsewhere, e.g.:

24 Nov: ban on more than 8 people gathering
7 Dec: schools for 16+ shut
18 Dec: mask guidance (not law) on public transport
24 Dec: some restrictions on bars
Taking account of the lag from infections, the positive test & ICU data suggest infections peaked around 16th December.

Definitely too late for gatherings to be the cause. Probably too late for schools. Clearly too early for the mask guidance or bar restrictions.
Read 5 tweets
18 Jan
Some people have been worried about high numbers of pupils attending schools since 4 Jan.

Children are (generally) not at risk of serious illness but concern was new variant wd cause fast spread in children, which cd then spill over to others.

We now some early data to look at.
First positive tests (7-day ave) for 5-9 & 10-14s. Allowing a 7-day lag to test, infections seem to increase during 1st part of holidays (but beware Christmas testing effects), then decrease from end of Dec. Early days, but so far looks like the decrease has continued since 4 Jan
Next NHS Covid-19 triage for U19s. Lag probably shorter than for tests.

7-day ave trend suggests infections leading to triage decrease before schools shut for Christmas, level off during holidays & then decrease again from about 4 Jan.

(Thanks to @dontbetyet for the chart)
Read 4 tweets
16 Jan
This is an interesting read by @cjsnowdon but not sure his examples necessarily support his case.

Take Ireland: Level 5 lockdown restrictions (pubs, cafes hairdressers shut) started on 24 Dec. The vertical rise in cases started 8 days after that on 2 Jan & continued to 8 Jan. Image
More restrictions were added up until 31st Dec & cases started dropping from the 9th. But you could just as easily claim the 24th Dec restrictions caused the vertical rise on the 2nd as to claim the extra restrictions caused the drop on the 9th.
I don't think Ireland reports by specimen date & also there were reporting lags. So probably pretty hard to be certain about any cause & effect, but it's not exactly a poster case for lockdown restrictions.
Read 7 tweets

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