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On 11 March Chancellor Merkel warned that the SARS-CoV-2 – the virus for the COVID-19 – could infect between 60 and 70% of Germany’s population (DW, “Coronavirus: Germany’s Angela Merkel urges ‘solidarity and reason‘”, 11 March 2020). She was accused to spread panic (Ibid.). Chancellor Merkel’s point was to highlight the very real danger Germans faced.

In this article, we explain why, indeed, as stressed by Chancellor Merkel, a pandemic such as the COVD-19 is something serious. We do so by establishing a crude baseline worst case scenario that helps us assessing the magnitude of the threat. The seriousness of the danger then determines why political authorities must consider the pandemic and why they need to take such drastic measures as complete lockdown of countries. Most importantly the severity of the threat determines actions and then real impacts. Meanwhile, we also explain how the rate Chancellor Merkel used was calculated.

A threat to life primes any other concern

Since the start of the pandemic, then still an outbreak, many commentators permanently try to minimize the possible extent of the threat. Rather than getting rational assessments and scenarios with acknowledgment of uncertainty and proper probability, we hear and read a vast array of comments and opinions most of them aimed at being positive, minimising problems, putting the economy first, while also often mocking others. As we pointed out earlier, this most probably stems also from the various interests of actors, added to many cognitive biases (see The Coronavirus COVID-19 Epidemic Outbreak is Not Only about a New Virus and The New Coronavirus COVID-19 Mystery – Fact-Checking).

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Nonetheless, we must remember that the fundamental mission of political authorities is to ensure the security of those they rules (see What is Political Risk?). Meanwhile, and as fundamentally, individuals want to survive. Thus, when a very direct threat to life, such as a virus and its related disease, emerges and spreads, then, very rapidly, all other matters loose importance. Actually, the rapidity of the understanding of the magnitude of the threat will also determine the measures taken and the very actualisation of the threat.

Thus, the problem is to evaluate the potential direct threat to life, at individual and collective level.

How to evaluate the potential direct threat to life?

Uncertainty and being careful with what we know through the Chinese experience

Because the virus is new, and as all serious scientific actors dealing with the SARS-CoV-2 and the COVID-19 permanently stress, much is still unknown about both the virus and the disease.

Furthermore, most of what we know about the illness and its spread comes from China. It thus includes the way the Chinese handled the epidemic. Our current knowledge thus contains elements about the virus and the disease that can be universally applied, as well as, possibly, idiosyncrasies. We should not forget that China deployed gigantic means to face the epidemic (Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) – 16-24 February 2020). These means and actions influenced the way the disease “behaved”.

They may also have influenced the virus itself. Indeed, and even though further research is needed, in an early study, Xiaolu Tang, Changcheng Wu, et al. found, studying the genomes of the SARS-CoV-2, that

“… these viruses evolved into two major types (designated L and S) … Whereas the L type was more prevalent in the early stages of the outbreak in Wuhan, the frequency of the L type decreased after early January 2020. Human intervention may have placed more severe selective pressure on the L type, which might be more aggressive and spread more quickly. On the other hand, the S type, which is evolutionarily older and less aggressive, might have increased in relative frequency due to relatively weaker selective pressure.” “On the origin and continuing evolution of SARS-CoV-2“, National Science Review, , nwaa036,

Xiaolu Tang, Changcheng Wu, Xiang Li, Yuhe Song, Xinmin Yao, Xinkai Wu, Yuange Duan, Hong Zhang, Yirong Wang, Zhaohui Qian, Jie Cui, Jian Lu, “On the origin and continuing evolution of SARS-CoV-2“, National Science Review, 03 March 2020,

Thus, we must be very careful when applying the “Chinese” experience elsewhere. We must work at distinguishing variables and at understanding the processes and dynamics at hand. This is nothing knew in science, as comparative approaches are, for example, detailed in John Stuart Mills’ A System of Logic (1843) with the method of agreement, of difference and combinations thereof (e.g. Encyclopaedia Britannica).

Using a crude baseline “worst case” scenario

We are thus faced with a lethal threat incorporating many unknowns, even after two and a half months, which, by the way, in scientific terms is an extraordinarily short time. Now, humanity has known throughout history many epidemics and pandemics, and is thus aware of the possible catastrophe a disease spreading entails. But what is meant by a possible catastrophe?

Scientific communications and articles, as well as political ones, most of the time, shy away from giving absolute numbers.This is probably partly for fear to create a panic, out of humility because we do not really know, and out of anxiety at being later targeted as having been wrong. However, then, it becomes truly hard to understand the threat.

To know the risks we face, to be able to better understand what could happen, what is a catastrophe, then we need to be able to get an idea of the threat one can represent. The threat must mean something. This implies having at least a crude worst case baseline scenario in terms of fatalities. In other words, we need to have an idea of what would be likely to happen if we were not acting. The aim here is not to get something precise and accurate, but to have an imperfect idea of the possible magnitude of the cost in human lives terms.

A crude estimate of the lethal power of the COVID-19 threat

To be able to get a crude worst case baseline scenario, we need to have first a possible figure for the number of people that could be infected, if nothing at all were done. Of course, each country and each actor is already doing a lot. Thus, as highlighted, this crude baseline worst case will explain why various authorities are fighting against the pandemic. It will indicate the magnitude of the threat and thus of the responses.

We shall follow here epidemiologist Roy M. Anderson et al., who explains that

“A simple calculation gives the fraction likely to be infected without mitigation. This fraction is roughly 1–1/R0.”

Roy M Anderson, Hans Heesterbeek, Don Klinkenberg, T Déirdre Hollingsworth, “How will country-based mitigation measures influence the course of the COVID-19 epidemic?” – The Lancet – Published online March 09, 2020

As we explained, R0 (R-nought) or basic reproduction number of an infectious disease is a measure that represents “the expected number of secondary cases produced by a typical infected individual early in an epidemic” (O Diekmann; J.A.P. Heesterbeek and J.A.J. Metz (1990). “On the definition and the computation of the basic reproduction ratio R0 in models for infectious diseases in heterogeneous populations”Journal of Mathematical Biology 28: 356–382).

This is most probably the calculation that is behind Chancellor Merkel’s figure for the rate of Germans the SARS-CoV-2 will probably infect (Ibid.).

We now have a range of possibles R0 for the COVID-19. The R0 have been estimated to be between 1.6 and 3.8 (see The New Coronavirus COVID-19 Mystery – Fact-Checking). Of course, the R0 evolves with time and actions, but we are only looking for a rough estimate. Anderson et al. use a R0 = 2.6 for their crude estimate, which corresponds to 61.54%, and is within the 60% to 70% range given by Chancellor Merkel.

Using these R0, we thus have the following worst case baseline scenarios table, for the world, with an estimated population of 7.7 billion people:

R0 1,6




% of infected population: 1–1/R037,50 %

54,54 %

61,54 %

73,68 %

Estimated case fatality rate 0,3 %1 %2,2 %3,18 % 0,3 %1 %2,2 %3,18 %0,3 %1 %2,2 %3,18 % 0,3 %1 %2,2 %3,18 %
Infected population in million 2887,5 4200,0 4738,5 5673,7
Estimated deaths in million8,728,9 63,5 91,812,642,092,4133,614,247,4104,2150,717,056,7124,8180,4

Thus, at worst, considering what is known of the SARS-CoV-2 and estimated by 12 March 2020, assuming no action had been taken, we could have had to face between 8.7 and 180.4 million direct deaths worldwide.

It is important here to stress that the estimates are for direct deaths. Indeed, if we consider the Italian tragic situation, the case-fatality rate is much higher and reached a staggering 6.7% on 12 March 2020. Pr. Ricciardi gives various possible causes for the much higher CFR in Italy, ranging from ways to establish statistics to impacts of overwhelmed hospitals on death rate ( Coronavirus, contagiati e morti: cosa succederà in Usa, Francia e Germania. Parla Ricciardi (Oms-Salute)). The latter notably can be seen as indirect and cascading – yet very real – causes of death. They are thus not included in the crude estimate calculated here.

COVID-19 Worst Case Baseline Crude Estimate –
World potential deaths if nothing had been done – The first four columns correspond to estimates for a R0 = to 1.6 thus 37.5% of the population infected. The next four to estimates for a R0 = to 2.2 thus 54.54%% of the population infected, etc. – Within each group of four columns, the first corresponds to a CFR = 0.3%, the second to a CFR = 1% then a CRF = 2,2%, and finally a CFR= 3,8%

If we consider that the fatalities for World War II were between 70 and 85 million, then, at worst, the COVID-19 could have been more than twice as deadly.

You can do the math for each country. For China, for example, the potential fatalities could have meant between 1.6 and 32.4 million deaths; for the U.S. between 0.4 and 7.6 million deaths.

Assuming China has indeed completely overcome the threat and is not infected again by other countries as they become prey to the epidemic, the possible global fatalities are now lower. The baseline threat is nonetheless still there for other countries. And some risk remain also for China.

Those figures are indeed just crude estimates, but the very high possible impact justifies the immense efforts made. It justifies that each and every person takes the pandemic seriously.

And here, the sufferings of the 13.8% that will probably have severe disease and the 6.1% that will be in critical conditions is not taken into account (Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) – 16-24 February 2020, p.12.). If we apply the same calculation, in the case of a R0 = 2.6, thus of 61.5 % of the population being infected, this means that, without any action 653.9 million people would be at risk to suffer severely and 289 million would be in critical condition.

The staggering difference between the rough calculation above and the reality, in China, of the detected cases – 80945 on 13 March 2020 – then fatalities – 3180 – is both a tribute to the success of the mammoth Chinese efforts (WHO report, ibid.) and a twin warning. First, the difference between real and estimated figures stresses that rough worst case estimates are nothing more than a crude evaluation of the danger faced. Second, and maybe most importantly, the difference between actual figures and estimated ones also underlines that gigantic efforts may not be an option but an imperative necessity.

Featured image: John Hopkins CSSE: Tracking the COVID-19 (ex 2019-nCoV) spread in real-time – map for 13 March 2020 – 17:43 CET.

A short summary FAQ

Can we create worst case scenarios for the COVID-19 pandemic?

Yes, definitely, we can. We can use estimates of scientific measurements to assess worst cases for the COVID-19 pandemic. This is actually necessary to know the extent of the threat, the risk and thus decide about the magnitude of the answers.

What could be the number of deaths caused by the COVID-19?

Worldwide, at worst, considering what is known of the SARS-CoV-2 and estimated by 12 March 2020, assuming no action had been taken, we could have had to face between 8.7 and 180.4 million direct deaths.
This means the COVID-19 could have been more than twice as deadly as World War II.

About the author: Dr Helene Lavoix (MSc PhD Lond)

Dr Helene Lavoix, PhD Lond (International Relations), is the Director of The Red (Team) Analysis Society. She is specialised in strategic foresight and warning for national and international security issues. Her current focus is on Artificial Intelligence, Quantum Science, and Security. She teaches at Master level at SciencesPo-PSIA.

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