Thread by @karamballes

1/🧵Thread Part II: 22nd April
Trial experiments in schools to replace isolation with 7 days of LFDs

Prior trials and DfEs scientific basis for continuing.

Still feels like playing guinea pigs to me

2/ A small number of trials went ahead.
Heads opted in, only identified close contacts who chose to replace isolation with DCT had to give consent.

NHS letter to a head setting out the details

3/ I have queried if the data for the November trials has been made available and how these results informed this new round of trials.

Awaiting answers, will share when I get them

Also hoping to find out who makes up the Independent ethics committee that signed this off

4/ DfE say the trials were based on this non-peer reviewed SPI-M-O paper on modelling from start of March.

Their logic is that introducing DCT will increase adherence to LFD surveillance testing and isolation.

gov.uk/government/pub…

5/ Thanks to @dgurdasani1 for our chat today on this document, valuable analysis as always.

I'll give a rough summary of my understanding of some of the issues with this paper to get the conversation going until one of the serious scientists like her have time for better detail

6/ The model used is from November, pre understanding B117.

First it says LFTs ONLY 12% less effective than a 14 day quarantine. I dont like the use of only when we are dealing with consequences of a nasty virus which can explode into exponential.

Demonstrates priorities.

7/The central model they base this on assumed 50% adherence to quarantine and 67% adherence to isolation due to symptoms or a
positive test.

Where do they get this adherence number on which the modelling depends? 100% of identified in
school contacts currently isolate

8/ Tried to explain this

Do they think adherence to isolation is only 50% when they included students being contacts
outside of school?
Do they think adherence to LFDs is so low that this equates to only 50%
of asymptomatic cases quarantining?

9/ What data do they have on take up of twice a week LFD data?

Their own modelling says that if take up of LFD is already high then DCT will increase transmission
Says wiith quarantine while DCT would be marginally better than DCT and skipping isolation even with 100%compliance

10/ The more detailed issues are around sensitivity and accuracy, thresholds for infectiousness and some assumptions around faster contact tracing.

11/The paper sets out the questions it thinks it answers

12/ It all comes down to behaviour.

An assumption is made that those not currently adhering to the rules will decide to start adhering to them if DCT is an option.

To balance the increased risk of not isolating this requires a significant increase in adherence.

13/ To justify this going ahead they need to show that adherence is low, and explain why they think this will see a large increase in adherence.

Even then they still haven't solved the massive consent issue.

But even then the logic is still twisted.

14/ If the problem is lack of adherence because people don't want to risk isolating, the solution isn't to potentially increase risk by trying to do away with isolation

The solution is putting in the support people need to be able to isolate, something we keep telling government

15/The solution is also investing in ventilation and air filtration to cut down the chance of transmission in schools.

Surely these two options are more effective, considering the spending on LFDS they might be cheaper as well.

16/ List of schools involved in the trials, drop down menus in alphabetical grouping
nasuwt.org.uk/advice/health-…

17/ Example of a letter sent out by a trial school to parents

https://twitter.com/Parents_Utd/status/1385331764059586569?s=19

18/18 Is this about cutting transmission or cutting isolation for other reasons?

Government considering preventing masks in secondary classes next month to appease skeptics

And masks in primary, even voluntary ⬇️😞

🧵18/18

https://twitter.com/SarahDRasmussen/status/1385015734762459143?s=19

If anyone would like to express their concerns about the clinical testing trials the email address is
[e-mail]

Update: Been contacted by someone at one of the schools. They didn't volunteer, they were invited. After a webinar they declined to participate, their school is marked as N/A on the list so I assume that the other marked as N/A including Eton have also declined.

So it would be interesting to know the selection process for sending invites out to schools to participate, I assume they aimed for a geographical spread, did they look at school intake? What about school buildings as some are considerably more spacious than others