Archive for the ‘Corona Virus’ Category

COVID-19:Still Looking good, but stiiiiillll not over

May 17, 2021

Click for a larger image. Logarithmic graph showing positive caseshospital admissions and deaths since the start of the pandemic. The blue arrows show the dates of ‘opening’ events. See text for further details

Friends, so here we are, May 17th 2021, and I can finally resume the natural pastime of old men: sitting in cafes.

Obviously, matters pandemical are not ideal, but they are in my estimation looking good.

To explain my uncharacteristic positivity, allow me to remind you how this summer differs from last.

I know what happened last summer…

As we look at the figure above covering positive cases, hospital admissions and deaths across the pandemic, we see that the second wave began in July 2020 – when cases began to rise. This was before the end of the first wave as judged by the minimum in the rate of deaths.

And after cases started to rise hospital admissions and deaths both fell for a further two months!

So now we should focus our attention on cases for first signs of a problem.

However what matters is:

  • not the absolute number of cases,
  • not the population prevalence of cases
  • not even the rate of change of cases

What matters is this:

  • Is there the potential for the pandemic to expand into the general population and kill hundreds of thousands of people?

Last summer the answer was definitely ‘Yes’.

This summer the answer is probably ‘No’.

Why? Because 55% of the entire population, including practically all of the most vulnerable groups have received a first dose of the vaccine.

Together with the 10% (roughly) of the population who have had the disease, we are close to herd immunity.

Herd Immunity is not an on-off thing.

As the prevalence of immune people approaches a critical prevalence – probably around 66% for the coronavirus – the speed of viral transmission slows as the virus finds it increasingly difficult to move from an infected individual to a vulnerable individual.

Once the prevalence of immune people has passed the critical prevalence – chains of viral transmission decay with increasing rapidity as immunity prevalence approaches 100%. For any physicists reading – it’s a continuous phase transition.


Careful readers may have noticed that I slipped in an italicised  ‘probably’ a few paragraphs back. Things could still go wrong.

Most notably, one variant of the virus or another could acquire the ability to escape the immunising effects of the vaccine.

This is possible, but it is – as far as I can tell – not a very likely outcome.

What will happen next?

Click for a larger image. Logarithmic graph showing positive cases, since the start of 2021. The blue arrows show the dates of ‘opening’ events. See text for further details

The figure above shows that the ‘openings’ (shown as blue arrows) are having an effect, because after each ‘opening’ step, the rate at which cases are falling slows down, because viral transmission chains can spread further in the more liberal environments.

And since the start of May, the daily rate of positive cases has been rising slowly.

So after today, with one has to expect that the daily rate of positive cases will rise faster, and that numbers will probably not decline for several weeks or months.

Also, the potential for tourists and returning tourists to re-seed infections of different variants around the country is a concern.

And many people will be distressed by this rise in cases and the (probably) ineffective controls at the borders.

But, as I said above, in my opinion the key question is:

  • Is there the potential for the pandemic to expand into the general population and kill hundreds of thousands of people?

And as far as I can tell, the answer is ‘No’. Probably.

Retirement: One year on…

May 2, 2021

Click for a larger version. Clouds and blossoms. Sometimes I think to myself, it’s a wonderful world…

Friends, it is now one year (and a day or so) since I retired from NPL. And it’s been an… interesting year.

Please allow me a few moments of reflection.


It took months for the poison that flows through that institution to leave my system.

I wrote about it a bit, (here and here and here and here) but writing about the inanity of management systems and the poisonous individuals that colonise them is such a negative activity I felt obliged to just leave that all behind.

I did worry that I might miss the physics, but in fact I am doing much more physics now at home than I was at NPL.

In the same way that Neo could read the code in The Matrix, so I see the world. As I walk into Teddington for a cup of coffee each morning, I see in the blossoms and the clouds, multiple unfolding physical principles creating a world of beauty and wonder.

I literally catch my breath at the intricate complexity of it every day.


I have written a lot about the pandemic in the last year, but as I reflect on the year, I am genuinely lost for words.

Some of my articles on the subject now seem especially prescient. See for example this 1st January 2021 article which predicted the daily death toll in May 2021 would be roughly 75 people per day.

Click for larger view. Prediction of the daily death toll on 1st May 2021 – it’s a little pessimistic but not far off given that the UK’s vaccine rollout had barely begun.

And recent news stories that our Prime Minister said he would rather see “bodies piled high than have another lock down” finally explains why we did not lock down in October 2020. Read my article from 26th September 2020 here.

If these reports are correct, then the number of deaths personally ascribable to the Prime Minister’s actions is now way more than the 19,000 I estimated previously.

While I myself would not want to occupy such a job, I can’t imagine the depravity of someone who could make, and then fail to acknowledge such a catastrophic error.

Carbon dioxide

Retirement (and the tax-free lump sum from my pension) has allowed me to make headway on reducing my household’s carbon dioxide emissions.

The house now has triple-glazing and external wall insulation that have reduced the heating demand (and CO2 emissions) by more than 50%.

In the next few months I will install a heat pump and air conditioning which should reduce CO2 emissions by a further factor 4±1.

And our solar panel/battery combination will keep us more-or-less off-grid all summer.

But as I seek to become a genuine Carbonaut, I am faced with some terrible questions:

  • Can I live a life without milk in my tea?
  • Is a life without bacon every once in a while a life worth living?
  • And cheese? Could a life without 12-month old Davidstowe cheddar genuinely be called ‘living’?

I am writing in jest, but the questions are deadly serious.

In the coming year I will write about this more, but already there are tonnes of carbon dioxide which have not been emitted due to my actions.

By my anticipated date of death in 2040, I hope to have avoided at least 60 tonnes of carbon dioxide emissions.


I am feeling my age. I am in good health, but at 61 I am realistically in the last ‘third’ of my life.

And before the ravages of age slow me down, I realise I have a window of unknown length in which – perhaps for the first time in my life – I am genuinely free to do whatever I want to do.

What an exhilarating and terrifying challenge.

Thank you

And to all those people – genuine friends – who have communicated their support throughout this year – thank you.

COVID-19: Still looking good: Still not over

April 26, 2021

Click for a larger image. Logarithmic graph showing positive cases, daily hospital admissions and deaths throughout the course of the pandemic. See text for further details

Friends, three weeks ago I wrote.

… the statistics are looking better than one might have reasonably hoped for. The next concern is the way positive cases will respond to the 12th April re-opening. If positive cases do not rise too rapidly…

Positive Cases

As the figure above shows, positive cases are still twice as high as they were at their minimum in July 2020.

But they have not increased after each of the substantial openings at the start of March and the start of April. This is excellent news.

Click for a larger image. Logarithmic graph showing positive cases, since the start of 2021. The blue arrows show the dates of ‘opening’ events. See text for further details

It is clear that the ‘openings’ are having an effect, because the rate at which cases are falling slows down because viral transmission chains can spread further in the more liberal environment. But they are still going down.

Further, testing now is not quite directly comparable with testing in July 2020. Now we are doing a great deal of asymptomatic testing and are probably catching many sporadic cases that were not caught in 2020.

So things are looking good – but there are still 2000 new cases a day so the virus is still out there and ready to spread when it can.

Hospital admissions and deaths

The opening in July 2020 still has lessons for us. In particular, we saw then that hospital admissions and deaths were lagging indicators. And lagging by a very long time.

At the time what was happening was not clear (to me at least), but in retrospect it is very clear.

The virus was spreading (largely asymptomatically) amongst young people. And the delay before the spread reached the vulnerable population was close to 2 months!

The lesson for summer of 2021 is this: The virus is spreading amongst young people and as long as the the number of cases is declining this shows that collectively the vaccines, prior exposure and social distancing are keeping the chains of viral transmissions short.

But this environment is applying reproductive pressure on the virus. If we open up again too rapidly there exists the possibility – not a certainty – that variants will arise which can escape the vaccine. This would be ‘bad’.


Click for a larger image. Logarithmic graph showing COVID deaths, since October 2020. See text for further details

Pleasingly, as can be seen in the top graph, the rate at which deaths have declined has been much more rapid the rate at which cases and admissions have declined. I think this must be the effect of the vaccine.

But since the start of April the rate of decline has slowed and has shown non-random fluctuations. Similar effects can be seen in the top graph for the period in between the first and second waves. I think this is because deaths are arising from specific clusters.

As the vaccinations progress, those fluctuations will arise from ever smaller and more isolated clusters.

Then the fractional fluctuations should get larger and eventually the happy day will come when the seven-day average death rate will be zero – and I will be unable to plot it on my chart!


COVID-19: April Update

April 6, 2021

Friends, I have been too busy being busy to write about the pandemic – probably a good sign.

Things are still looking good in the UK and it seems likely – but not yet certain – that the government’s gamble has paid off.

Their gamble was that a single shot of the vaccine would offer enough initial protection to prevent a surge in infections and hospitalisations and deaths as we began to re-open society.

I am not one to offer praise to the government easily, but it was very smart to increase the spacing between the two vaccine doses, even though that was not the situation tested in the field trials.

The decision to do that was a smart ‘science-based’ policy decision rather than a bureaucratic ‘cover my own back’ policy decision.

What’s happening now?

The logarithmic graph below shows positive cases, hospital admissions and deaths since the start of the pandemic.

Click for a larger version

We see that positive cases, hospital admissions and are falling roughly as fast as they did after the first wave, halving in 21 days. But deaths are falling much faster. This is probably the vaccine at work.

We’ll look at each statistic in detail later, but here I will note that – as shown by the dotted lines in the above graph – compared with 4th July 2020 when the last opening up happened:

  • Positive cases are still much higher.
  • Hospital admissions and deaths are similar.

So there is still plenty of virus ‘out there’ and still plenty of un-infected un-vaccinated people under the age of 50 who can sustain the virus in the population.

But the most vulnerable 47% of the UK population have had a single-shot of vaccine and so this is unlikely to lead to the rise in hospital admissions and deaths that we saw after the first wave.

But note that after the first wave, hospital admissions did not start to rise for a full seven weeks after cases began to to rise.


Schools have re-opened and the consequent social mixing caused the rate of decline of daily cases to slow almost to a standstill.

Click for a larger version.

Subsequently  the rate of decline has picked up again, but we must anticipate that the 12th April re-openings will result in another pause.

I will be concentrating on that pause in the next couple of weeks to see if it is indeed a pause, or – and I hate to say it – the start of a third wave.

Hospitalisations and deaths

For completeness, here are the data on hospitalisations and deaths.

Click for a larger version.

Hospitalisations (above) still seem to be falling with a halving-time of around 21 days, but deaths (below) are falling much faster.

It is hard to conceive that this result must be anything other than close to the most optimistic of projections.

Click for a larger version.

The graph above is complicated. Deaths are shown against the logarithmic left-hand axis, and vaccinations in two shades of blue are shown against the linear right-hand axis.

Supply limitations have caused the first-shot extent to slow just below 50% of the entire population as vaccines are prioritised for second shots before the 12-week delay.


Given the appalling second-wave death toll, and the generally grim start to the year, the statistics are looking better than one might have reasonably hoped for.

The next concern is the way positive cases will respond to the 12th April re-opening.

If positive cases do not rise too rapidly, then we can hope that new vaccine deliveries later in April will allow the first shot vaccine drive to reach the 75% level required for herd immunity sometime in June.

And then perhaps we could all relax for a month or two.

COVID-19: What next?

March 14, 2021

Friends, if you are anything like me, you are most probably sick to death of this virus. And yet it goes on.

I have been looking back at my posts over 2020 and I still feel OK about most of my comments. But as we re-open schools I thought it would be an idea to look back at where we were last September 2020 when schools re-opened.

By 26th September 2020 it was obvious that the exponential growth in prevalence which marked the start of the second wave was underway. At the time I did not imagine that twice as many people would die in that second wave as in the first. I wrote: Here we go again.

I mention this because looking up the prevalence data today (below) I notice that the viral prevalence is currently greater than it was when schools last re-opened.

Click for a larger version. This

We are probably all more versed in anti-viral protocols than we were in September 2020, but nonetheless we have to expect some increase in viral transmission and prevalence.

The difference between then and now, is that now 35% of the UK population have had a single-shot of vaccine and a substantial number of the most vulnerable are fully immunised.

We should thus expect that rising cases will not necessarily lead to the same rise in hospital admissions and deaths that we saw previously.

What’s happening now?

The ONS prevalence data (above) necessarily lags what’s happening on the ground by about two weeks.

If we look at current cases, we can see that there has been a rise in cases – or at least a slowdown in the rate of decline –  in recent days.

An unknown fraction of this rise is definitely an artefact of the large number (more than 1 million per day) of lateral flow tests being done around the return to schooling. (See the first 20 minutes of this Independent Sage Presentation for an explanation). But the exact fraction is unclear.

Click for a larger version.

So at this point it is hard to know what this rise means: whether it could just be another wiggle. Or whether it could be – and I am being serious – the start of Wave 3.

If we look at the long term graph of positive cases, we see that back in July 2020 (~Day 191) when prevalence and cases were 10 times lower, cases suddenly began to rise and kept rising.

Click for a larger version.

Hospital Admissions and Deaths did not start to rise for another 8 weeks.

Click for a larger version.

This time – the vaccine makes things different – and in 8 weeks time a full 50% of the entire population should have had at least a first shot. So we should not expect a rises in cases to lead to rises in hospital admissions and deaths.

But if the viral prevalence becomes widespread again then we risk breeding variants that can spread under the new conditions in which they find themselves.

For completeness, here are the data on hospitalisations and deaths

Click for a larger version. The pink shading shows that hospitalisations have now fallen below their trend since late January 2021.

Click for a larger version. The pink shading shows that deaths have now fallen below their trend since late January 2021. The blue line shows 1st-shot vaccinations and the light blue line shows 2nd shot vaccinations . Dotted lines show projections and trends.

COVID-19 Milestones

March 4, 2021

Friends, allow me to highlight three upcoming COVID milestones.


  • First the positive: Tomorrow I will receive my first shot of vaccine. Hurray!
  • Second, and more tragically, tomorrow or Saturday will mark the date on which the death toll from the second wave will reach 82,732 which is double the death toll from the first wave. Words fail me.
  • Thirdly, Monday will mark the re-opening of schools. And two weeks later we will be able to see the effect on the rates of COVID cases.

Intriguingly, the populations who will be mixing (directly or indirectly) after schools re-open – parents, teachers, and children – will be mainly unvaccinated. But the most vulnerable people will be mainly vaccinated.

Measuring the resultant extra cases and the way they feed through to hospital admissions and deaths will likely be critical to the development of the Government’s ‘re-opening’ strategy.

Update on Cases

As I am sure you know the data are looking good – the daily rate of positive tests for COVID-19 is falling with a halving-time which may be even less than 16 days.

Click for a larger version.

The number of positive cases per day is shown above on a linear scale. The red dotted curve shows the rate at which cases fell after the first lockdown.

One can see that just over two weeks ago (~day 410) the rate at which the cases were falling reduced, but the rate of decrease now appears to be even faster than before – but we only have a few days data.

It is easier to see the trends if the data is plotted on a graph with a logarithmic vertical axis. On this graph (below) exponential trends show up as straight lines.

Extrapolating the trend of the last few days, we might hope for around 1000 cases per day by Easter (4th April). At that level, track, trace, support and isolate really should – after a year of utter failure – be able to cope.

However, we should more reasonably expect the rate at which cases are falling to slow (to some extent) after the schools re-open.

Click for a larger version.

Update on Hospital Admissions

The rate at which people are admitted to hospital is also falling, but unfortunately the data file of the ‘dashboard’ website is corrupted.

As you can see in the screenshot below for today 4th March 2021, the daily figure is 757. But in the data file, this figure is recorded as being appropriate to the 28th February. So using the data file would lead one to think that cases were falling more rapidly than they are.

Click for a larger version.

Using daily figures as they were reported, I find that hospital admissions are falling with a halving time of 21 days – surprisingly the same as after the first lockdown.

However the recent daily admissions data looks to have ‘steps’ in it – and given the errors above – it may not be reliable.

Click for a larger version.

Update on Deaths 

The rate at which people are dying from COVID is falling, faster and faster.

The figure below shows that after falling with an initial halving-time of about 16-days (orange dotted curve), daily deaths are now falling even faster.

The difference between the extrapolated 16-day halving time trend and the actual data is shaded in pink.

This is almost certainly the vaccine taking effect.

Click for a larger version.

Also shown in blue is percentage of the entire UK population (adults and children) who have received a first dose of vaccine.

The rate appears to have slowed a little in the last week or so – presumably as second-doses are prioritised.

Nonetheless, the rate is impressive: roughly 50% of the population will have received a first shot of vaccine by Easter.


So here we are… in the sad shadow of a gigantic second wave of deaths.

But with a little luck, the army of elderly vaccine gladiators which I will join tomorrow will vanquish the Covidian contagion before it can mutate.

Death to the Covidians!

COVID-19: The Johnson Plan

February 22, 2021

Friends, I just thought I would note down my first reflections on the latest plan of our Glorious Leader.

I actually skipped his TV announcement tonight to instead watch the NASA press conference releasing the video of the landing of Perseverance on Mars.

And the mindset of the engineers who made that landing happen is, by chance, relevant to our situation.

They achieved success by considering all the ways in which their mission could fail, and made a plan that avoided each failure mode in turn.

In other words, they achieved success by a relentless focus on failure.

This mindset does not seem to be part of the Government’s strategy.

Why do I say that?

Because announcing in advance that their policy will be “irreversible” is a mistake in the same category as calling The Titanic “unsinkable”.

The Johnson Plan

My first thought is that this would be nice if it all worked, but I find it hard to believe that it will – it seems too optimistic.

With regard to my comments above on the mentality that enabled NASA’s successful Mars landing, there appears to be no plans for failure. No plans with the structure of:

  • We expect X
  • If X doesn’t happen we will do Y.

Let me explain why I think that.

Yesterday I said the Government’s self-proclaimed focus on ‘data not dates’ should focus on monitoring the rate of daily positive cases. This is because hospital admissions and deaths follow cases.

So setting criteria for lifting restrictions based on cases enables a rapid response before hospital admissions and deaths follow.

Click for larger version. See text for details. Daily rate of positive Covid-19 tests since June 2020. The vertical axis is logarithmic so exponential rises and falls look like straight lines. The dotted lines show my extrapolations of the trend of the data.

The graph above shows how the daily case rate has varied since June 2020.

I have highlighted various events in amber ovals to show how clearly this graph speaks to us.

  • The first oval marks the ‘opening’ of society: pubs, restaurants and hairdressers. 
    • There were 600 cases/day
    • Cases immediately began to rise marking what is clearly the start of the Second Wave which has killed about 80,000 people (twice as many as the First Wave), brought untold misery to many, and devastated the economy more than many wars.
  • The second oval marks the return to school. 
    • Cases immediately rose from 1400/day to 2600/day in a week and kept rising.
  • The third oval marks the return to Universities. 
    • Cases immediately rose from 6200/day to 17500/day in a week and kept rising.

With the exception of Lockdowns, every Government action to tackle this was ineffective

So much for the past, what about the future?

The Johnson plan

Step 1 of the J-Plan calls for a widespread Return to School on 8th March 2021.

  • As the fourth oval shows, cases will then optimistically be in the range 4000/day to 9000/day, much higher than when children last returned to school in September 2020.
    • I find it hard to believe that this will not stimulate an immediate rise in cases, exactly as it did last time.
    • Test, Trace, Support and Isolate is still not functioning. Indeed it could never reasonably have coped with that many cases anyway.
    • If cases rise, will the Government reverse its irreversible course?
  • The fifth oval shows, the earliest date (12th April 2021) at which regular retail, personal care and outdoor hospitality will re-open.
    • This seems to predicated on case rates in the range 1000/day to 3000/day.
    • This rate is much higher than the case rate of 600/day when retail last opened in July 2020
  • The sixth oval shows the earliest date (17th May 2021) for Step 3. .
    • There is no point thinking about this because it’s just so unlikely.

The Impact of Vaccines

Of course the difference between ‘now’ (Ovals 4 & 5) and ‘then’ (Ovals 1, 2 and 3) is the role of vaccines.

If vaccines break the chains of viral transmission, then the Government’s plan may make sense, but I think that is unlikely to happen until later in the summer when the younger adult population and children are vaccinated.

More likely is that (in the next few months) the vaccines will reduce the burden of illness arising from cases. So hospital admissions and deaths may continue to fall even as cases rise.

This leaves open the possibility that for several months, viral prevalence may remain very high, leaving open the door for viral mutations with unknown properties. They could be benign, or deadly.

If the NASA team were planning this, they would see this as a deadly failure mode and plan for it.

My fear is that the Government will just hope for the best, but not make a plan to cope with it. Announcing in advance that your plan is “irreversible” does not inspire me.

COVID-19: Next Steps

February 21, 2021

Friends: This is how epidemics work:

The VIRUS causes CASES which cause HOSPITAL ADMISSIONS which cause DEATH

Click for a larger version. Remember that on a logarithmic graph, a straight line means that a quantity is increasing or decreasing exponentially.

The graph above shows the number of positive tests for COVID-19 per day, the number of hospital admissions per day, and the number of COVID-19 deaths per day since April 2020.

The link between these three quantities is clear.

Currently everything is terrible.

  • There are hundreds of people dying every day
  • Hospitals are full and many people with other illnesses cannot be treated.
  • The economy is badly damaged with consequent distress and unhappiness.
  • We can’t even hug the people we love.

But things are getting better.

  • The vaccines are here.
  • All the pandemical indicators are falling.

On the eve of the Government’s announcement of its ‘Get out of Lockdown Strategy’ in this post I will summarise my hopes and fears.


The graph below shows the number of positive tests for COVID-19 per day since July 2020.

Click for a larger version. Remember that on a logarithmic graph, a straight line means that a quantity is increasing or decreasing exponentially.

We see that currently the number of positive cases per day is halving roughly every 16 days – this decline is significantly faster than after the first wave.

  • Since the virus is now apparently more transmissible than the First Wave variant, this is a surprising fact.

However even if the trend continues, we will not be at the level at which First Wave restrictions were lifted (about 600 cases per day in July 2020) until May 2021.

With hindsight we can see that cases began to rise IMMEDIATELY Lockdown#1 ended, and this was indeed the start of a very large and deadly Second Wave.

So I hope the Prime Minister will:

  • Set a level of cases (say 1000 cases a day) that can trigger the lifting of particular sets of restrictions.
  • Make the test, trace, and isolate system work, and employ targeted isolation and local ‘ring’ vaccination campaigns around cases.
  • Set a second level of cases (say 2000 cases a day) that can trigger the re-imposing of particular sets of restrictions.
    • It is imperative that we do not let the virus run away again, and the first sign of viral spread is rising numbers of cases.

What I fear is that the Prime Minister will:

  • Set a level of ‘trigger’ cases (say 5,000 cases a day) which is too high for test, trace and isolate to cope with
  • Do nothing to rectify the flaws with test, trace and isolate.
  • Not announce in advance what will happen if cases rise.
  • Use the vaccination programme – which should have a detectable effect on deaths soon – to be used to as an excuse to allow lifting of restrictions.

However allowing the virus to spread amongst younger less-vulnerable people is a recipe for breeding strains of the virus with new properties.

Recall that currently nobody on Earth knows why COVID-19 affects older people more. It is perfectly conceivable that a new strain might cause harm to younger people. We should guard against any such possibility.


The graph below shows the number of hospital admission for COVID-19 per day since July 2020.

Click for a larger version. Remember that on a logarithmic graph, a straight line means that a quantity is increasing or decreasing exponentially.

Once again it is obvious in retrospect that once admissions stopped falling at the start of August – about a month after cases began to rise – the Second Wave was with us.

Nothing the Government did (with the exception of National Lockdowns) made any difference. Remember that roughly 25% of those admissions resulted in death.

This graph makes it clear that it is the virus which is still in charge.

So I hope the Prime Minister will:

  • Announce that after restrictions are lifted (based on a cases criterion), any rise at all in hospital admissions will cause a re-imposition of restrictions.

This is essential so that hospitals do not once again become COVID-hospitals.

One last curiosity is that  hospital admissions are falling at the same rate – roughly halving every 21 days – as after the First Wave.

  • Since the cases are falling faster, this indicates an increasing ratio of admissions to cases – I do not know why.


The graph below shows the number of COVID-19 death per day during the Second Wave.

Click for larger version

Like cases, but unlike admissions, deaths are falling with a halving-time of roughly 16 days – rather faster than after the First Wave.

  • I do not know why!

I don’t have the skill to make a model to simulate how the protective effect of the vaccine will translate into lower death rates. But qualitatively I would expect the death rate to plummet shortly.

My hope is that the Prime Minister will:

  • Ignore the death rate in setting criteria for re-opening.

My reasoning here is simple: until we have full population vaccination, wherever the virus goes, cases, hospital admissions and then deaths will follow.

So increasing cases and admissions are omens of impending increases in the death rate.

  • The counterargument to this is that if death rates fall – because of vaccination – then the harm caused by the virus is eliminated, so why not lift restrictions?
  • The reason is that if COVID-19 is widespread in the population it will likely mutate under selection pressure. Only if we drive the prevalence of the virus to extremely low levels can we minimise the risk of a harmful mutation arising.


Currently everything is terrible, but things are getting better.

My recommendations are (I hope) clear, but I do not live with the same pressure that the Prime Minister has to.

And with regards to schools in particular, the pressure to re-open is immense.

From a pandemical point of view, I would say it is too early to re-open schools: the prevalence is too high and re-opening will almost certainly increase the spread of the virus, which test trace and isolate will probably fail to contain.

And re-opening risks the breeding of a new Summer Term strain of virus with potentially appalling properties.

However the Prime Minister may consider this a chance worth taking to re-start education.

I’m glad I don’t have that job.


COVID-19: The risk to men

February 17, 2021

Click for a larger version. Output from the QCOVID calculator showing the risk arising from ethnicity and biological sex compared to a 61-year old woman.

Friends, you may have read recently (e.g. The Guardian) of a new tools for analysing the risks of dying from COVID-19 including many different risk factors, including ethnicity.

The tool – called QCOVID – is available for you to use here.

Media coverage generally highlighted the relative risks appropriate to different ethnic minorities.

For some reason, the media did not mention the most prevalent risk factor for dying from COVID-19: being male.


As one does, I immediately typed in my own basic statistics: I am a white male aged 61 with a BMI of 24.8. The result was this:

Click for a larger version. Output from the QCOVID calculator for someone with my vital statistics.

I took note of the absolute risk of a COVID associated death: my risk was 0.0173% over a 90-day period i.e. a risk 1 in 5,780.

I then changed the ethnicity and biological sexuality entries to the calculator across a number of categories.

Changing ‘my’ biological sexuality to female I saw that ‘my’ risk went down to 0.0077% over a 90-day period i.e. a risk 1 in 12,987.

So the additional risk factor associated with being a biological male was 2.2.

Click for a larger version. Output from the QCOVID calculator showing the risk arising from ethnicity and biological sex compared to a 61-year old woman.

I was curious as to how this compared with differences arising from ethnicity and the results relative to the ‘Me-female’ are shown in the table above.

I found the results striking.

  • For females, the additional ethnic risk factors ranged from 1.2 to 2.0. In comparison the additional risk factor of being a white male was 2.2
  • In every ethnic category, being male carried an additional risk factor varying from 2.2 to 4.6 compared to the equivalent female.


I did not investigate all the various categories in the QCOVID calculator, so I cannot confirm the complete generality of this result.

But from my simple investigation, I conclude that:

  • Men of any ethnicity are at least twice as likely to die from COVID-19 as women from the same ethnic background.
  • The additional risk faced by women associated with their ethnicity is less than the additional risk faced by white males associated with their sexuality.

My question is this: why has this dramatic result affecting millions of people not been reported more widely?

Update 19th February

A correspondent pointed out in the comments this excellent data source

This site shows that excess mortality amongst men occurs worldwide, but the extent of it is highly variable from one country to another.

I don’t have an explanation of this phenomenon, but it does appear to be very real, whatever its cause.



Covid-19: Quick Update

February 15, 2021

Click for a larger version. The number of positive CV cases per day shown a daily data (dots) and as a 7-day retrospective average. The data re plotted on a logarithmic axis. Presented in this way, exponential trends appear as straight lines. The rates of decline are highlighted and extrapolated by dotted lines. It is clear that the rate of decline of cases has changed – it is now halving every 16 days  – much faster than the initial rate of halving every 21 days, and faster than it did after Lockdown#1.

As I have mentioned before (1, 2) the daily rate of positive cases is falling faster than it did after previous lockdowns.

As you can see on the graph above, the halving-time for cases is now 16 days rather than roughly 21 days after the first lockdown.

The difference has been sustained for 4 weeks which is long enough to arise from something other than chance.

I cannot tell if it arises from the vaccination programme, but if the trend continues…

  • …we will reach 1000 cases per day in mid-April rather than mid-May

This is significant. 1000 cases per day is probably the maximum rate that our embarrassing Test, Trace and Isolate system might be expected to cope with.

So – good news! But I wish I knew why!

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