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Dr Duncan Robertson

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5 Oct, 9 tweets, 3 min read

We may be systematically underestimating R by excluding students in halls of residence. A Thread

https://twitter.com/Dr_D_Robertson/status/1312865098843779083

We know that data on the Government Coronavirus dashboard is unreliable (see this thread)

https://twitter.com/Dr_D_Robertson/status/1312865098843779083

https://twitter.com/Dr_D_Robertson/status/1312821471618662401

We also know that we are not doing enough testing as the positivity rate is so high (7% overall for Pillar 2 tests and up to 15% in some areas such as Liverpool) (see this thread)

https://twitter.com/Dr_D_Robertson/status/1312821471618662401

So, how do we go about estimating R? Here's a thread I wrote in January explaining R in relation to Covid-19 (which then didn't have an official name) duncanrobertson.com/2020/01/24/con…

To estimate R, we carry out surveys - which means you pick a representative group of people, either households or individuals, and test them repeatedly.

There are two main surveys: ONS and REACT

ONS excludes student halls of residence, as 'only private residential households, otherwise known as the target population in this bulletin, are included in the sample. People in hospitals, care homes and other institutional settings are not included'
ons.gov.uk/peoplepopulati…

This is confirmed here sciencemediacentre.org/expert-reactio…

The REACT survey uses GP lists to generate its sample of people who are tested.

But of course, new students are only just registering with their GPs, and it is unclear when the GP lists were pulled for the latest study (Round 5 of REACT-1, 18-26 Sep)

imperial.ac.uk/media/imperial…

We know that halls of residence are a significant driver of transmission.

We may be systematically under-sampling from halls of residence and therefore systematically underestimating R.

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More from @Dr_D_Robertson

Dr Duncan Robertson

@Dr_D_Robertson

4 Oct

Nearly 23,000 Covid-19 cases were reported today. This is due to a delay.

Analysis thread.

Public Health England have released a statement. It is here: gov.uk/government/new…

First, note that the Department of Health and Social care is the data controller for Pillar 2 tests. It passes these data to Public Health England, and DHSC are responsible for the data.

The statement says:
"we have identified that 15,841 cases between 25 September and 2 October were not included in the reported daily COVID-19 cases"

Read 14 tweets

Dr Duncan Robertson

@Dr_D_Robertson

4 Oct

New York compared with Liverpool: Schools

A Thread

@WSJ

The @WSJ is reporting that

"New York City on Wednesday will close public schools and nonessential businesses in parts of Brooklyn and Queens that have registered a week-long spike in coronavirus cases"

wsj.com/articles/new-y…

Let's look at New York and then compare to a UK city, Liverpool.

Read 13 tweets

Dr Duncan Robertson

@Dr_D_Robertson

3 Oct

@NAOorguk

.@NAOorguk @CommonsSTC - can you investigate the delays in today's Covid reporting? If it's just a delay in reporting, that's one thing, but if these are delays into NHS Test and Trace system, that's another thing entirely. Would be good to see age/source of delayed cases

https://twitter.com/avds/status/1312481833347502080

It is important to understand the reason for the delay. If this is a reporting delay, that is bad enough, but if there have been delays in putting these cases into the NHS Test and Trace database, that can have serious implications for spreading the disease

We also need to know if there is commonality in the source of these cases. We have seen that private testing and university testing has been carried out, and it is still not clear how these results (both positive and negative) are being routed into the DHSC system.

Read 7 tweets

Dr Duncan Robertson

@Dr_D_Robertson

2 Oct

The latest Covid surveillance report has been published by Public Health England. Here is my commentary. The main point is that Covid is now widely established, not only in the north and the midlands but also north London and for the first time in Cornwall

@WHO

The data is for week 39 (between 21 September and 27 September. First, positivity. This is the number of positive cases divided by the number of tests. It's now around 7%. THIS MEANS THAT NOT ENOUGH TESTS ARE BEING PERFORMED (@WHO recommend this does not exceed 5%)

Age pyramid of cases in the last two weeks. Mostly capturing younger people.

Read 15 tweets

Dr Duncan Robertson

@Dr_D_Robertson

2 Oct

@OfficialUoM

Well done to @OfficialUoM for publishing positive Covid cases at the university. manchester.ac.uk/coronavirus/ca… This draws attention to the university, and raises questions as to why this hasn't been updated for a few days. But it is a good thing to be public, and should be encouraged.

@sheffielduni

.@sheffielduni also publish data - well done, particularly for keeping the info up to date. sheffield.ac.uk/autumn-term-20…

@UniofExeter

We can see apparent outbreaks at other universities. Here's the location of @UniofExeter (21-27 September cases) - would be good to have a dashboard of cases.

Read 8 tweets