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Dr Duncan Robertson

11 Nov, 9 tweets, 2 min read

This is the evaluation report for the Innova lateral flow device tests that are currently being used in the Liverpool pilot.

ox.ac.uk/news/2020-11-1…

This updates prior work where they were only shown to 'pass' the tests

gov.uk/government/pub…

"The specificity of the test was recorded as 99.68% - the overall false positive rate was 0.32%, although this was lowered to 0.06% in a lab setting."

"It has an overall sensitivity of 76.8% for all PCR positive individuals but detects over 95% of individuals with high viral loads, and minimal difference between the ability of the test to pick up viral antigens in symptomatic and asymptomatic individuals."

These LFD tests are not as good at picking up cases as PCR tests.

In the case of the Innova results, it would pick up around 76.8% of those that would test positive using PCR tests (the ones we have been using)

Link to the full evaluation report here

ox.ac.uk/sites/files/ox…

An advantage of these tests is that they are quick.

They can be used as part of the testing strategy.

But - importantly - if you receive a negative result, it does *not* mean that you do not have Covid.

https://twitter.com/ScienceShared/status/1326563891766243329?s=19

Further commentary here

https://twitter.com/ScienceShared/status/1326563891766243329?s=19

These were the papers considered by SAGE on mass testing

Consensus statement prepared by the Multidisciplinary Task and Finish Group on Mass Testing (TFMS) for the Scientific Advisory Group for Emergencies (SAGE).

assets.publishing.service.gov.uk/government/upl…

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More from @Dr_D_Robertson

Dr Duncan Robertson

@Dr_D_Robertson

13 Nov

Here is my thread showing my new heatmaps for detected cases, positivity, hospital and ICU admissions.

We have reached the grim milestone of over 200 cases per 100,000 in the over-80s. There were 8 cases per 100,000 in this age group in August.

Not all cases are detected.

Monochrome version

Positivity of tests for males in Pillar 2. Positivity is the number of people testing positive divided by the number of people tested. Greater than 5% means that not enough testing is being done.

Each age group for males exceeds 5% positivity.

Read 6 tweets

Dr Duncan Robertson

@Dr_D_Robertson

12 Nov

33,470 Covid cases were reported today, significantly above yesterday's 22,950 cases

This does not appear to be due to cases being disproportionately added in Liverpool due to Lateral Flow Device testing - ( table below based on that from

)

@avds

* This does not appear to be due to cases being disproportionately added in Liverpool due to Lateral Flow Device testing - ( table below based on that from @avds )

Read 4 tweets

Dr Duncan Robertson

@Dr_D_Robertson

12 Nov

PHE have released their latest Covid surveillance report

It is for week 46, showing up to week 45 data (2-8 November 2020)

Significant all-cause deaths were observed in week 44 (as well as week 43) overall in England , and in the 75-84 age group.
assets.publishing.service.gov.uk/government/upl…

Confirmed Covid cases increasing.

Positivity decreasing slightly (but still very high in Pillar 2 testing)

Age distribution of detected cases in the last two weeks

Read 23 tweets

Dr Duncan Robertson

@Dr_D_Robertson

11 Nov

Guidance for universities / students for returning home:
- what lateral flow device (LFD) tests are being used
- what is the sensitivity of these tests
- how is the risk of testing negative being communicated
- what are the results of the Liverpool pilot

gov.uk/government/pub…

The guidance discussed the high specificity of the tests but is silent on the sensitivity.

The guidance says
"This will provide additional assurances that where tests are negative, there is a reduced risk in students travelling home, and a reduced risk of transmission to their family and home community."

But this does *not* mean you will not be infectious.

Read 5 tweets

Dr Duncan Robertson

@Dr_D_Robertson

7 Nov

@PHE_uk

Here is my latest heatmap of detected Covid-19 cases in England. Data from @PHE_uk

*** 177 *** cases per 100,000 in the over-80s.

There were **8** cases per 100,000 in the over-80s in late August.

See the positivity chart in this thread to show that many cases go undetected.

@PHE_uk

Colourblind-safe heatmap of detected Covid-19 cases in England. Data from @PHE_uk

Positivity of tests for males in Pillar 2. Anything above 5% means we are not testing enough people.

*All* age groups in males are not tested sufficiently.

There is a significant issue with males not being tested sufficiently.

Read 6 tweets

Dr Duncan Robertson

@Dr_D_Robertson

6 Nov

The updated SPI-M slides - a short thread on what's changed.

On 31 September, in a hastily arranged press conference, the Chief Scientific Adviser presented these two slides, showing projections for hospital admissions and deaths.

These were subsequently revised

The first slide shows a *projection* for hopsital admissions. On the left, the oringial slide, on the right, the amended slide.

These slides present a *range* of the projection (the shaded blue area), and a central projection (the dark blue line).

The upper level for the range of the projection has changed but *the central projection* (the dark blue line) *has not changed*

Read 17 tweets

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