COVID-19: Day 115: About half-way through.

Warning: Discussing death is difficult, and if you feel you will be offended by this discussion, please don’t read any further.

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Today is Day 115 of 2020 and as I stare again at the COVID-19 data, two things seem particularly striking.

The first thing is that – as we pass 20,000 deaths – we are only halfway there. My expectation is that another 20,000 people will yet die from from COVID-19 over the next 50 days or so.

And the second thing is that on Monday March 23rd, when the UK ‘locked down’ – the cumulative number of deaths was 280. This is less than 1% of the number of people who would eventually die. And yet at that point, we were in some sense already committed to the astonishing total of deaths we are facing.

Thing#1: Halfway 

I have been look ahead to see what we might expect to happen in the coming days and weeks.

I assumed that:

  • 19% of people diagnosed with COVID-19 using ‘Pillar-1’ testing in hospitals will die after – on average – 6 days. This is 1% less than I assumed previously, but seems to match the recent data better.
  • The number of Pillar-1 confirmed cases is declining linearly. These are mainly patients being admitted to hospital.

Based on these assumptions I have calculated the expected cumulative totals of confirmed cases and consequent deaths.

Slide1

The above graph shows various statistics plotted versus the day of the year.

  • The vertical green lines show the date of the ‘lock down’, the end of ‘phase 1’ of the ‘lock down’, and the upcoming end of ‘phase 2’.
  • The blue curve shows the cumulative number of ‘Pillar 1 tested’ COVID-19 cases.
  • The red curve shows the cumulative total of COVID-19 deaths in hospital.
  • The black dotted line shows the predicted number of deaths based on
    • 19% case mortality after 6 days.
    • A continuation of the current linear decline in Pillar 1 cases.

There is considerable uncertainty in this projection. But I think it represents a fair expectation.

It indicates that in terms of deaths,
we are still only half-way through.

Thing#2: Growth Rate

Slide2

The above graph shows various statistics plotted versus the day of the year.

  • The vertical green lines show the date of the ‘lock down’, the end of ‘phase 1’ of the ‘lock down’, and the upcoming end of ‘phase 2’.
  • The blue curve shows the cumulative number of ‘Pillar 1 tested’ COVID-19 cases.
  • The black dotted line shows the predicted number of cases based on a continuation of the current linear decline in Pillar 1 cases.

There is considerable uncertainty in this projection. But I think it represents a fair expectation.

What also struck me here was that on Day 81, at the start of the original ‘lock down’, there had only been 280 deaths and the daily death rate was about 50 people per day. And yet this relatively small number was a sign of a tsunami of illness about to overwhelm our country.

By acting then we have undoubtedly saved the lives of probably hundreds of thousands of people.

Thing#3: Life after Day 123 (3rd May)

On day 123, the cumulative total of people testing positive for the corona virus as they entered hospital will be approximately 150,000. 

Based on the loose statistic that 20% of people require hospital treatment, we can guess that

  • the cumulative number of true cases in the population is around 750,000.
  • a significant fraction of these people will have had the illness and recovered.

Thus after 3rd May, the number of people who will be unwell will be much less than 1% of the population.

So relying on chance alone, for every 100 people one meets, 99 will be virus free.

It seems to me that even with substantial relaxation of our current social distancing, it will likely be possible to keep the chance of person-to-person virus transmission low.

But given the sensitivity I mentioned in Thing#2 – we will need to remain vigilant.

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Discussing death is difficult, and if you have been offended by this discussion, I apologise. The reason I have written this is that I feel it is important that we all try to understand what is happening.

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