COVID-19: Day 289: Looking really bleak…

Things are looking bleak.

Twenty days ago on 26th September 2020 I wrote that we appeared to be committed to COVID death rates of around 100 people per day in mid-October. Sadly, yesterday – October 15th – the 7-day average of the daily death rate reached 100.

That prediction is testament to the super-power of “looking on a log graph of the data and drawing a straight line“.

Using the same superpower, I would estimate that we are  probably already committed to more than 200 deaths per day – possibly as many as 300 deaths per day – at the end of October.

Are the new policy responses sufficiently strong to cause a decline in viral prevalence? I would love to be wrong, but personally, I don’t think so. I’ll write more about what to expect at the end of the article.

Let’s take a look at the data.

Data#1. Prevalence

Since late April the ONS prevalence survey has been randomly testing people each week to look for the virus. They then collate their data into fortnightly periods to increase the sensitivity of their tests. Details of their full results are described methodically in this ‘bulletin‘.

The latest fortnightly data point is highlighted in red. Click for a larger version.

The number of people tested and the number of positive tests are given in their table above. ONS estimate that at the end of the measurement period on 8th October 2020 on average 0.7% of the UK population were actively infected. They estimated the prevalence was 1.43% in the North West of England and 0.34% in the South East.

The raw count of positive tests was:

  • 926 from 154,664 people tested in the two weeks to 8th October,
  • 250 from 103,220 people tested in the preceding two weeks, and
  • 89 from 68,272 people tested in the two weeks preceding that.

Note these are random survey tests (so-called Pillar 4 tests), not clinical tests.

Their data – graphed below – suggest that the prevalence is now doubling roughly every 11 days.

I have shown two exponential curves on the graph below.

  • The black dotted line (– – –) is the same curve I plotted for the previous three weeks (last week, the week beforethe week before that). It is a fit to the 3 black data points and shows what we might expect if viral prevalence were doubling every 15 days.
    • Last week’s and this week’s updates lie significantly above the extrapolation.
  • The purple dotted line (– – –) is a fit to the last three data points from today’s data set. It shows what we might expect if viral prevalence were doubling every 11 days.

If one considers it likely (which I do) that the viral prevalence has continued on trends similar to the ones shown, then today (16th October) the prevalence is likely to be around 2% i.e. roughly 1 in 50 people in England are infected right now. Regionally it might even approach 3% – roughly 1 in 33.

Estimated prevalence of COVID-19 in England. Click for a larger version.

Data#2. Tests and Deaths

The graph below shows three quantities on the same logarithmic scale:

  • the number of positive tests per day
  • the number of people newly admitted to hospital each day
  • the number of deaths per day.

The data were downloaded from the government’s ‘dashboard’ site.

  • Positive tests refer to Pillar 1 (hospital) and Pillar 2 (community) tests combined – not the Pillar 4 tests from the ONS survey.
  • The deaths refer to deaths within 28 days of a test.
  • Hospital admissions for the UK nations combined.

All curves are 7-day retrospective rolling averages of the data since July.

Data for positive cases, daily hospital admissions and daily deaths. Click for a larger version.

The graph shows the data alongside exponentially decreasing and then increasing trends shown as dotted lines.

  • The declining trends correspond to quantities halving every 21 days.
  • The increasing trends correspond to quantities doubling every 15 days.

We see that the three data sets initially fell with similar time-dependencies. All the quantities are now rising.

  • The rate of positive tests and the rate of hospital admissions seem to be doubling every 15 days.
  • The rate of deaths appears to be close to doubling every 11 days – this is shown as an additional dotted line on the death data.

What Next?

As I write, our best guess is that roughly 2.0% of the UK population are actively infected with the virus. I am personally alarmed by this figure.

  • Using my super-power of ‘drawing a straight line through the data and extending it‘ I estimate that we are already committed to at least 200 COVID-related deaths per day by the end of October. Nothing can be done about these deaths because the people are already infected and ill.
  • With the prevalence doubling every 11 days then, 100 deaths per day now will turn into 800 deaths per day in 33 days i.e. by mid-November. This would be another national catastrophe.

This week the government have taken action with their 3-tier response. From midnight tonight, households throughout London will be forbidden from visiting each other. In Liverpool and Lancashire the restrictions are even stricter. However, it is likely that adherence to these restrictions will be less perfect than during the spring lock-down. Schools and Universities will remain open.

If the measures achieved R = 1, which I consider very unlikely – then the death rate would stay at whatever level it was when R = 1 was achieved. Because we have acted so late, even achieving R = 1 would simply keep the death rate at it is current high level.

More likely, the measures will not achieve R = 1 but rather something just over 1. This will increase the doubling-time from the present value of (very roughly) 11 to 15 days to something longer – perhaps 30 days. This would then commit us to a death rate of perhaps 400 people per day at the end of November and perhaps 800 people per day at Christmas.

In my opinion…

  • We need to reduce the spread of the virus – not just slow it down. Action on this is long overdue and the current policy response will probably not achieve that, even at Tier 3.
  • ‘Full’ lock downs – as we had in the spring – are the only thing which has been demonstrated to reduce the prevalence of the virus. And even the spring lock-down only halved the incidence of the virus every 21 days.
  • The cost of lock-downs is immense in every dimension, but I personally think when death rates reach many hundreds per day – which is where they are headed – then a full lock down will be politically inevitable.
  • It is better to acknowledge the awful reality we are in and plan a series of lock-downs while the death rate is low than to wait until the rate is high.
  • If this epidemic lasts for a further 6 months before a vaccine arrives, then every extra 100 deaths per day amounts to an additional 18,000 deaths before the end of March 2021.

Like I said, things are looking very bleak.

Stay safe.

Estimated prevalence of COVID-19 in England. Click for a larger version.

Saturday 17th October 2020: Typos corrected

One Response to “COVID-19: Day 289: Looking really bleak…”

  1. Andy Henson Says:

    First class analysis and commentary, thanks Michael

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