A decision will shortly be made about whether we should move to Step 2 of the Roadmap for unlocking

The premise of moving to the next step is that it should be led by:
- data not dates; & be
- irreversible

A thread with my thoughts using the latest data.
The Roadmap tests are:

1. The vaccine deployment programme continues successfully
2. Evidence shows vaccines are sufficiently effective in reducing hospitalisations and deaths in those vaccinated
...
3. Infection rates do not risk a surge in hospitalisations which would put unsustainable pressure on the NHS
4. Our assessment of the risks is not fundamentally changed by new Variants of Concern
Cases data is unreliable due to the mixture of LFD and PCR testing. Given this caveat, the detected cases data shows increases in the 10-19 age group but decreases in all other age groups.

This is expected as increased interaction following children returning to school.
Cases by themselves are not one of the four Roadmap tests.

I anticipate that cases will rise in the 20-40 year old populations in the weeks to come as cases spread to parents and carers.

Hopefully LFD testing for school children and households will mitigate some of this effect.
Positivity (number of people testing positive divided by the number of people taking tests) is very low in 10-19 year olds as there are millions of LFD tests taken.

However, 5-9 year olds do not (generally) take LFD tests, so a fall in positivity here is encouraging.
Looking at Roadmap Test 3:

3. Infection rates do not risk a surge in hospitalisations which would put unsustainable pressure on the NHS

we can use hospitalization and ICU admissions data.

Hospitalizations falling in all age groups (except for under 5s - small numbers admitted)
Looking at Roadmap Test 2:

2. Evidence shows vaccines are sufficiently effective in reducing hospitalisations and deaths in those vaccinated

ICU admissions are relatively low. Note that '0' does not mean no admissions, just 0 per 100,000 when rounded to the nearest whole number
Looking at Roadmap Test 1:

1. The vaccine deployment programme continues successfully

we can look at the roll out of vaccines.

Still very encouraging - not 100% coverage, which means many people still vulnerable. Mainly first doses.
And finally, Roadmap Test 4

4. Our assessment of the risks is not fundamentally changed by new Variants of Concern

This is the test that in my opinion causes the greatest risk.

Cases are dominated by the B.1.1.7 variant. Note log scale and *cumulative* chart.
Stripping out B.1.1.7 and looking at this *cumulative* chart, we still see increases in the B.1.351 (South Africa, purple line) variant and the P1 (Manaus, Brazil, red line) Variants of Concern.

Numbers will have been biased by surge testing, but increasing numbers shows a risk
Going back to the Roadmap:

Tests 1-3 are generally positive but there remains a risk
Test 4 (variants) is where there is potential high risk.

However, the constraint that the steps should be 'irreversible' means that ministers should be *very* aware of the risks they are taking
We remain in a battle between the Virus, Vaccines, and Variants.

Opening up further will mean that groups not previously in contact will mix meaning new chains of infection

*When* to open up remains a political decision.

As ever, advisers advise and ministers decide.

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More from @Dr_D_Robertson

26 Mar
Virus, vaccines, and variants. My heatmaps for cases, positivity, hospitalizations, ICU admissions in England.

New this week - charts for vaccine takeup and variants.

Vaccines - good; variants - concerning. We need to ensure that we use the data before unlocking further.
All charts this week start from the start of the vaccine rollout and show the (very severe) third wave.
Detected cases.

Increasing in 10-19 year olds (likely due to lateral flow testing in schools).

Increasing in 5-9 year olds. These are not routinely given lateral flow tests.

Other ages - rates decreasing.
Read 10 tweets
18 Mar
Public Health England @PHE_uk have published the update for variants of concern and variants under investigation. Note that these are cases detected (and that these may be detected as the result of surge testing).

Rises in VUI B.1.525 (+26 since Tuesday) & VUI B1.1.318 (+10)
Here is the data table (data from @PHE_uk). Note B.1.1.7 is excluded in the chart above. To emphasise, these are the result of non-uniform testing and sequencing.
Description of variants (from @PHE_uk):

The VOC-20DEC-01 variant was first detected in the UK and was first sequenced in the UK in September 2020.

The VOC-20DEC-02 variant was first detected in South Africa and was first sequenced in the UK in December 2020.
Read 8 tweets
24 Feb
Public Health England @PHE_uk have published a report on prevalence of Covid in the university student population.

A very short thread.

Publication here:
papers.ssrn.com/sol3/papers.cf…
They find that fewer than 1 in 5 students (17.8%) had antibodies at the end of the Autumn term (which imples that more than 80% were susceptible to Covid).

"SARS-CoV-2 seroprevalence in 2,905 university students was 17.8% (95%CI, 16.5-19.3) ..."
"... ranging between 7.6%-29.7% across the five universities" (the universities are not named - 'University A' to 'University E')
Read 6 tweets
22 Feb
The Government's roadmap for reopening has been published.

I will add commentary as I read through.

From first glance, there are no numbers for thresholds, which does in some way question the notion of 'data not dates'.

There are however a lot of dates in the document.
The roadmap itself is only 15 pages long.
It sets out 'principles'
- whole of England rather than regional response
- "led by data not dates" (see above)
- five weeks between steps - 'no earlier than'
- face-to-face education a priority
Read 17 tweets
22 Feb
Today the Prime Minister will announce the roadmap out of lockdown. A short thread.
First of all, a reprise of previous attempts at coming out of lockdown. They haven't gone well.

So, what is the plan for release of lockdown this time? At the moment, this is what we have to go on.

We are told this is "cautious"
gov.uk/government/new…
Read 13 tweets
21 Feb
On the face of it, this does seem to be more weighted to dates rather than data.

It will be interesting to see if *any* quantitative thresholds for cases, hospitalizations, or pressure on hospitals are set out on Monday, or whether the only thing that are set are dates.
It is obviously a risk, I'd reports are correct, to send all school children back on the same date. One critical thing missing is the ability to adapt. If R exceeds 1 and hospitalizations increase as a result of this, all that can be done is to close face to face...
schooling with the effect this will have on children's continuity of education. It would be prudent to send *some* children back and see the effect before committing all children.

Remember, it is not just the interactions between children (which *could* be mitigated...
Read 6 tweets

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