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SARS-CoV-2 genome: A=Purple T=Orange C=Yellow G=Red[1]

The physician and health researcher Hans Rosling regarded the greatest risks to human civilisation as global pandemic, financial collapse, world war, climate change, and extreme poverty.[2] Could the coronavirus disease (COVID-19)[3] which emerged in Wuhan, China, in late 2019, and in early 2020 reached pandemic status, be the pandemic Rosling feared?

The 1918 Spanish Flu killed up to 100 million people in a year, and in the 14th century the Black Death killed between a quarter and a half of the populations it affected,[4] but neither destroyed civilisation (although the plague resulted in widespread social changes in its aftermath).[5]

Modelling work by researchers at Imperial College[6] suggest that, with no action by governments, the Coronavirus would kill around 2 million people in the US and half a million in the UK.[7] With drastic measures to suppress spread of the virus the death toll could have been kept to below 20,000 in Britain (the researchers didn't publish figures for the USA).

What makes the big difference in numbers?

The flat red line is the capacity of the health system to cope with critical care patients

The Imperial College researchers modelled various scenarios for mitigating the spread of the disease, aiming to find a strategy which kept the numbers of people so badly affected that they need hospital treatment within the resources of the health system to treat them. Put bluntly, without hospital treatment, and especially without the availability of ventilators to assist breathing, most people who need treatment will die. With treatment about half will survive.

The model showed that none of the mitigation strategies which were less disruptive to society than a full lockdown kept the epidemic from overwhelming the resources of the health service.

However even the severe lockdown strategy does not halt the spread of the virus; it just reduces it to a low level, which will spring back again when and if restrictions are lifted.

Without suppression the epidemic might lead to enough survivors having acquired immunity to the disease[8] to protect those who have not yet had it via herd immunity. This was the UK government's strategy before the Imperial study was published,[9][10] despite the larger, avoidable, toll of death, injury[11] and suffering it would entail, and despite the government knowing from the experience of Asian countries which have successfully contained the virus, the recommendation of the WHO, and advice in The Lancet, that suppression is the correct, effective response.[12]

Without the possibility of herd immunity we need a vaccine to end the infection, just as the advent of vaccines ended outbreaks of smallpox, diptheria, polio etc (and might have eradicated measles had non-medical factors not intervened[13]). However it is estimated that it will take 12 to 18 months for a safe and effective vaccine to be available and widely deployed, so in the meantime how do we cope?

Adaptive triggering of restrictions depending on number of ICU cases

The Imperial team found that cases could be kept below a level which overwhelms health facilities if restrictions of social distancing etc are relaxed only when the number of cases in Intensive Care Units fall below a certain threshold (e.g. 50 cases per week), and are re-imposed when ICU cases rise above another, higher, threshold (such as 100 cases/week).

How accurate is the Imperial College modelling?

Models, whether of climate, epidemics, or any other real world phenomena, make assumptions about the systems they are trying to represent, in order to make the model manageable.

Such simplifying assumptions result in models being somewhat inaccurate.

The resultant inaccuracies may not necessarily be small: in some systems there may be tipping points, where small changes result in large consequences, such as a small increase in heating of the Arctic causing ice to melt allows more heat to be absorbed by the darker, more heat-absorbent surface of the sea.

Some real-world systems have random, chaotic components: the so-called Butterfly Effect from the metaphorical example of the formation and path of a tornado being influenced by minor perturbations such as the flapping of the wings of a distant butterfly several weeks earlier. A model of such a system might produce different results every time the program is run, even with the same starting conditions. Running the model lots of times would produce a variety of results, which can be compared to see what real-world results are more likely and which are less probable.

Another source of inaccuracies are errors in the model, or its implementation as a computer program. The latter are alleged in an article[14] on an anti-lockdown website with Conservative links[15] and cited approvingly by a prominent climate denialist website[16] However even if Ferguson's team's model is erroneous, the course of the epidemic in various parts of the world since the publication of their report in mid-March shows that the course of the epidemic can be either mild, if tackled effectively as a few countries have managed, or severe as in Italy before action was taken, and in the UK and USA where disease has extracted the highest death tolls in the world.

How does C19 compare with Spanish and ordinary flu?

COVID-19 compared to Spanish and seasonal flu[17]

The best-case figure for UK COVID-19 deaths with vigorous mitigation measures is 20,000 people.[6] The population of the UK is about 66 million, so that is 0.03% of the population, or about one person in three thousand.

The figure of 510,000 in the UK without mitigation is 0.77%, or about one in every 130.[6]

For comparison the death rate from Spanish flu has been estimated at somewhere between 0.8% (one in 125) and 5.5% (one in 18).[18]

Ordinary seasonal flu claims about 0.05% (about one in twenty thousand).[18]

Thus the worst case for an unmitigated Coronavirus epidemic is similar to the lowest estimate of the death rate of the 1918 Spanish Flu.

However the Spanish flu pandemic was over a century ago, at a time when one in ten babies died before reaching their first year and life expectancy was far lower, even in the UK, which was then the most prosperous country in the world.[19] Public health, and health expectations amongst the public, have changed radically in the intervening years, and the grim death toll of the earlier pandemic would today be regarded as horrific – and no doubt politically unacceptable, if it were known that an alternative were possible.

How does C19 compare with other causes of death?

COVID-19 compared to other causes of death[17]

Deaths from air pollution in the UK are 0.1% (about one in every thousand) per year.[20]

The UK has an average of 32,000 excess deaths each winter (0.05%, or one in two thousand) of which 9,700 (0.015%, one in seven thousand) were due to cold homes.[21] In the winter of 2017-2018 the number dying due to cold homes peaked at 17,000 (0.026%, one in four thousand).[22]

World-wide about 1.5 million people – mostly young children – still die of vaccine-preventable diseases. That's 0.02%, or one in five thousand.[23]

In the UK about 2000 people are killed on the roads each year: 0.003% (about one in forty thousand).[24]

An unmitigated COVID-19 epidemic would be a public health (and possibly political) disaster, but with effective mitigation the health effects could have been brought down to levels comparable with other public health issues, some of which claim even more lives.

Ironically the reduction in activity, especially traffic, brought about by lockdown has caused a reduction in air pollution which may result in compensatory fewer deaths overall (although the effects of pre-existing air pollution is likely to exacerbate the health effects of the virus).

Suppressing the Coronavirus

Outcomes with the lowest death tolls depend on drastic measures to suppress spread of the virus:

  • social distancing of the entire population,
  • isolation of all cases,
  • quarantine of entire households where anyone is sick, and
  • closure of all schools and universities,

and for these measures to be maintained, on and off, for 12 to 18 months, until a vaccine is available.[25] These measures will be hugely disruptive on many levels: physical, economic, social, and possibly political.

Social distancing

Compared to attempting to quarantine affected populations (or doing nothing) social distancing, where people reduce their contact with others, works best for slowing the spread of the virus. This article shows graphically how effective these approaches are.[26]

Such extreme and rigorous distancing requires that most of the population, except workers in health and other essential services, stay at home for the duration of virus-suppression periods of several months at a time. Obviously this requires that those staying at home have means to live on: food, fuel, electricity, internet and health care. And that those without homes have them. Otherwise the effort to suppress the virus will take longer, or fail altogether, as those in hardship because of isolation are liable to go out to try to find work or the resources to support themselves. This poses challenges in societies run along neo-liberal lines where the practical necessity of supporting all sections of the population clashes with the ideology of requiring everyone to pay for most of their needs. In the UK MPs from different parties, charities, and think tanks, urged the government to provide financial support to all those self isolating, especially when sick, as other countries have done.[27] and the government has broken with prevailing financial policies to provide support those employees unable to work, but little has been done for the significant portion of the population who are self-employed, let alone those who fall between the cracks of such provisions. This threatens all parts of society: even royalty and prime ministers are not immune to the problem.

Before and after COVID-19

The "19" in the name refers to the year in which this particular Coronavirus was identified: late 2019. Over a decade earlier a paper discussing the first SARS-Coronavirus epidemic of 2003 noted that "[t]he presence of a large reservoir of SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern China, is a time bomb. The possibility of the reemergence of SARS and other novel viruses from animals or laboratories and therefore the need for preparedness should not be ignored."[28][29]

If we are not to spend much of future years and decades in and out of states of lockdown[30] then we need to change aspects of human civilisation to reduce our risks and increase our preparedness to tackle challenges.

British agriculture minister John Selwyn Gummer feeds a beefburger to his daughter in front of journalists during the BSE crisis

One way in which we make ourselves vulnerable is through our relationships with animals. The C19 virus is thought to have crossed from bats to humans in a "wet market" in Wuhan, China, where live wild animals are traded,[31] but there are also hazards from our interactions with, and exploitation of, domesticated animals. The practice of feeding the ground-up remains of dead animals to live cattle resulted in "Mad Cow Disease", and its transmission to humans as variant Creutzfeldt–Jakob disease. The widespread prophylactic use of antibiotics in animal farming risks contributing to antibiotic resistance which poses a huge threat to human welfare.[32][33]

In the context of global heating, the land required for animal – especially cattle – farming, and the land required to grow food for animals, is increasingly obtained by deforestation, which releases CO
and interferes with the ability of large forests such as the Amazon to create their own rain-producing climate. Even where forest is not cleared, the land used for animal farming represents an opportunity cost; if it weren't being used for raising animals it could be used for rewilding/reforestation, solar farms etc.

We need to have grown-up conversations about the relative rights of those who want to eat their favourite foods, whether bat or beef, versus the rights to health, and even survival, of their fellow-humans.

See also: Q&A: Could climate change and biodiversity loss raise the risk of pandemics? in Carbon Brief on 15 May 2020

It is not yet known exactly what triggered the current outbreak, but researchers suspect that the virus passed from bats to humans through an unknown intermediary animal, possibly a pangolin.

Politicians in the UK have called this pandemic a “once-in-a-century” crisis. But scientists have warned that the ongoing disturbance of species through human activities and climate change could be raising the risk of potentially pandemic-causing diseases passing from animals to humans.

The study of the “spillover” of disease from animals to humans has received renewed focus in light of the pandemic. The Intergovernmental Panel on Climate Change (IPCC) – a major international collaboration of climate scientists – is now looking into how the influence of warming on such events could be included in its next major climate report due next year.

In this explainer, Carbon Brief examines what is known about how climate change and biodiversity disturbance, including habitat loss and human-animal conflict, could influence the risk of diseases being transmitted from animals to humans.


Another issue we need to tackle is the resilience and spare capacity, not only of our health systems but of all services on which we depend.

Heavy cuts to UK health services resulting in worsening responses to demand[34] and the routine overworking of its doctors deplete rather than enhance the ability of the British NHS to cope with emergencies such as C19. Systems such as the US' in which around a tenth of the population has no health cover[35] are poorly-equipped to tackle epidemics.

In an era of climate change bringing challenges of wildfires, flooding, increasingly frequent and severe storms, drought, extreme heat, harvest failure, and disease, civilisations need to build resilience to cope. The economic pressure to reduce costs, from health provision to just-in-time supply chains, needs to be countered by deliberate provision for resilience. Possibly economic measures along the lines of carbon pricing which place monetary values on resilience services may provide a solution for economies run along free market lines. But whatever mechanism is preferred, the need to achieve greater resilience is clear.

Other resources

The World Health Organisation's information on COVID-19 is here.

Our World In Data has an article on COVID-19 statistics and research, and other articles.

This YouTube video by ‘Kurzgesagt – In a Nutshell‘ in collaboration with Our World In Data explains much about COVID19 and its consequences for individuals and society.

Footnotes and references

  1. The SARS-CoV-2 genome comprises 8 kilobytes of data, 29,903 base pairs of RNA. When this little string-shaped molecule gets inside a human cell, in its little delivery package, it codes for its own reproduction plus packaging for the new strings, and that is enough to bring the world to its knees. Graphic by /u/dx8xb. Data from Pubmed, GenBank MN908947.3 (From Facebook post by Zi Teng Wang)
  2. "Factfulness: Ten Reasons We're Wrong About the World – and Why Things Are Better Than You Think" by Hans Rosling, Ola Rosling, and Anna Rosling Rönnlund
  3. The virus which causes the COVID-19 disease is called severe acute respiratory syndrome coronavirus 2 (abbreviated as SARS-CoV-2)
  4. "In the Battle Against Coronavirus, Humanity Lacks Leadership" by Yuval Noah Harari in Time on 15 March 2020
  5. "Social and Economic Effects of the Black Death" by Bright Hub Education, observes that

    Before the plague, peasant serfs were confined to their lord’s estate and received little or no payment for their work . Overpopulation and shortage of resources led to malnutrition and extreme poverty for many peasants. After so many people died, serfs were free to move to other estates that provided better conditions and receive top pay for their work. Landowners, desperate for their labor, often provided free tools, housing, seed and farmland . The worker farmed all he could and paid only the rent.

    Serfs improved their standard of living too. Modern day archaeologists have found evidence that prior to the Black Death, most of the peasants relied on clay pots to cook their meals but in years following the plague pandemic, households used more expensive metal cookware.

  6. 6.0 6.1 6.2 "Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand" by Neil M Ferguson and others on behalf of the Imperial College COVID-19 Response Team; 16 March 2020
  7. From p7 of the Imperial paper: "In total, in an unmitigated epidemic, we would predict approximately 510,000 deaths in GB and 2.2 million in the US, not accounting for the potential negative effects of health systems being overwhelmed on mortality.
  8. This assumes that survivors do develop immunity to the virus; this is expected from experience with other, similar, viruses, but is not certain, and it is known how long such immunity might last.
  9. "The UK's coronavirus policy may sound scientific. It isn't" by Nassim Nicholas Taleb and Yaneer Bar-Yam in The Guardian on 25 March 2020
  10. See video in Tweet by @Haggis_UK

    piersmorgan & Matt Hancock go head to head over Dominic Cummings very controversial remarks.. as reported in the Sunday Times. 1/2

    Cummings - "Protect the economy & if that means some pensioners die, too bad"

  11. It is thought that some of those who recover from the disease may suffer long term lung damage.
  12. "Boris Johnson wasted seven weeks talking nonsense about coronavirus, says expert" by Mike Sivier in Vox on 21 March 2020
  13. "Andrew Wakefield" Wikipedia
  14. "Code Review of Ferguson’s Model" by Sue Denim on Lockdown Sceptics on 6 May 2020
  15. The "Lockdown Sceptics" site carries links, and has many similarities in website construction, to the "Free Speech Union" (e.g. compare source of with
    The "Free Speech Union" was founded by the Conservative Toby Young (see Young's tweet "Join me in the Free Speech Union and together we can defeat the authoritarianism and intolerance that is once again threatening to destroy our liberty."
  16. "Brutal Takedown of Neil Ferguson’s Model" by Charles Rotter on 6 May 2020 on Watts Up With That
  17. 17.0 17.1 spreadsheet
  18. 18.0 18.1 "The Spanish flu (1918-20): The global impact of the largest influenza pandemic in history" by Max Roser in Our World In Data on 4 March 2020
  19. "The impact of the Great War on Infant Mortality in London" by Jay Winter, Jon Lawrence, and Jackie Ariouat in Annales de Démographie Historique Année, 1993
  20. "Cardiovascular disease burden from ambient air pollution in Europe reassessed using novel hazard ratio functions" by Jos Lelieveld, Klaus Klingmüller, Andrea Pozzer, Ulrich Pöschl, Mohammed Fnais, Andreas Daiber, and Thomas Münzel in European Heart Journal on 21 May 2019
    See also "Air pollution responsible for more deaths than smoking, study says" by Alex Matthews-King in The Independent on 12 Mar 2019
  21. "UK has sixth-highest rate of excess winter deaths in Europe" by E3G on 23 Feb 2018
  22. "17,000 people in the UK died last winter due to cold housing" by E3G on 15 Feb 2018
  23. "Global decline in vaccine-preventable diseases" by by Samantha Vanderslott, Bernadeta Dadonaite and Max Roser in Our World In Data on July 2015 (revised Dec 2019)
  24. "Reported road casualties in Great Britain: quarterly provisional estimates year ending June 2018" by Department of Transport on 8 Nov 2018
  25. "A chilling scientific paper helped upend U.S. and U.K. coronavirus strategies" by William Booth in The Washington Post (via on 19th March 2020.
  26. "Why outbreaks like coronavirus spread exponentially and how to "flatten the curve"" by Harry Stevens in The Washington Post on 14 March 2020
  27. "Calls for UK basic income payment to cushion coronavirus impact" by Robert Booth and Heather Stewart in The Guardian on 19 March 2020
  28. "Severe Acute Respiratory Syndrome Coronavirus as an Agent of Emerging and Reemerging Infection" by Vincent C. C. Cheng, Susanna K. P. Lau, Patrick C. Y. Woo, Kwok Yung Yuen in Clinical Microbiology Reviews Oct 2007, 20 (4) 660-694; DOI: 10.1128/CMR.00023-07
  29. See also: "Infectious diseases emerging from Chinese wet-markets: zoonotic origins of severe respiratory viral infections" by P C Woo, S K Lau, K Y Yuen in Current opinion in infectious diseases, Oct 2006
  30. "We’re not going back to normal" by Gideon Lichfield in MIT Technology Review on 17 Mar 2020

    Social distancing is here to stay for much more than a few weeks. It will upend our way of life, in some ways forever.

  31. "Bats are not to blame for coronavirus. Humans are" by Nick Paton Walsh and Vasco Cotovio, in CNN on 20 March 2020
  32. "A Review of Antibiotic Use in Food Animals: Perspective, Policy, and Potential" by Timothy F. Landers, Bevin Cohen, Thomas E. Wittum, and Elaine L. Larson in Public Health Reports, Jan-Feb 2012
  33. "Tackling antibiotic resistance from a food safety perspective in Europe" by the World Health Organisation
  34. From "What’s going on with A&E waiting times? by the Kings Fund, updated 25 March 2020:

    A&E waiting times have worsened substantially over the past decade, as the NHS has experienced a sustained period of financial austerity and staffing pressures. The NHS has not met the four-hour standard at national level in any year since 2013/14, and the standard has been missed in every month since July 2015

  35. "Key Facts about the Uninsured Population" by Jennifer Tolbert, Kendal Orgera, Natalie Singer, and Anthony Damico in Kaiser Family Foundation on 13 Dec 2019