Behind the numbers, the picture of the killer coronavirus is becoming clearer.



The coronavirus pandemic is generating intense research activity around the world. Scientists are working to better understand and respond to the new virus. They are helped by the astronomical amounts of data accumulated day after day and freely shared by the entire scientific community. A mass of statistics among which are probably hidden keys to understanding. This is what Professor Jean-François Toussaint, a specialist in the field, and his team at Irmes, the first to have demonstrated through the in-depth analysis of statistics of various kinds, the human limitations both in life expectancy and performance. His research into the figures of the current pandemic is beginning to reveal information of crucial importance, some of which goes against the certainties and assertions being conveyed these days. The professor has agreed to share his first results, still in the exploration phase, for UP' readers.


The coronavirus spreads between 25° and 55° North latitude.

Maps of the spread of the virus are widely distributed by several agencies. Those of the Johns Hopkins University are the most frequently used, updated in real time. They show the contaminated areas on a map of the world, showing red spots of varying sizes corresponding to the intensity of the number of patients in a given country. At the time of writing this article, the Johns Hopkins map is as follows:

Map published by Johns Hopkins University - 25/03/2020

The densest red areas are found in a band in the Northern Hemisphere. Jean-François Toussaint and his team noticed that this zone was precisely located between 25° and 55° North latitude. « It is in this area that 99 % of the lethality of VIDOC-19 "says the researcher.

Latitude and number of deaths (Log10) Source : IRMES and Johns Hopkins CSSE 25/3/20

The virus would have found its preferred "niche" in this area. This raises several questions. The first is population density.

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Population density does not have an impact

Does the virus find its home in the densely populated areas of this northern hemisphere band, which would make sense? For Professor Toussaint's team, there is no correlation between population density and the nature of the epidemic. Scientists have carefully studied very dense regions such as Hubei in China, the epicentre of the epidemic. They have looked at even denser regions such as Macao or Hong Kong. They went to see what was happening in a very densely populated area like South Korea. In all cases, however, they saw no impact of this factor on the dynamics and intensity of the epidemic.

The North-South gradient is massive

However, the researchers observed that the further north one goes, the greater the gap between the "official" date of entry of the virus (the first "national" contamination declared by a citizen) and the day when the curve starts to move significantly: from the moment the tenth case occurs, the curve accelerates exponentially.

The further north you go, the more the virulence of the pandemic aggression diminishes.However, the time between the first contamination and the tenth death is increasing with latitude. « The further north you go, the more the virulence of the pandemic aggression diminishes. Because of this, the countries of Northern Europe will not experience the intensity of the two major crises we are seeing in Italy and Spain. " says Professor Toussaint. It is then clearer why the weapons of containment are not yet drawn in Sweden.

The target of the virus is the very elderly

For Professor Toussaint's team, the virus, regardless of density, would rather target a population on which it would activate its expansion. One of the most relevant factors is the age of the population.

The risk explodes with age says Professor Toussaint. In the first published series,no deaths are recorded below the age of 50; then, it increases gradually: 10% of mortality between 80 and 90 years old; 35% beyond that. "After the age of 80, the risk of dying from coronavirus, once contracted, is 100 times greater than that of a person in their forties.

Age and mortality of VIDOC 19 - Source: Remuzzi A, Lancet 2020 and Korean CDC Update on Covid19

Young Protectors

By observing the age pyramid of the countries concerned, the researchers analysed the ratio of people over 70 to people under 20. In a pyramid of very young countries, such as the emerging countries, a very broad base can be seen and therefore a ratio is very low. This is the case in some provinces of China, Iran and even Korea, which have a ratio of 0.23, i.e. there are 4 people under 20 years old for every person over 70.

Conversely, ageing populations in Western Europe, Italy or Spain hold the record for life expectancy, but have a ratio of more than 0.8: i.e. 4 people over 70 years old for every 5 people under 20 years old.

The hypothesis to be tested is that the younger group may be protective of the older group. Ninety year olds in the middle of a population of people under 20 years of age - who are known to contract much less disease and have a much lower viral load than others - could protect the older ones by a mass or "mass effect". herd immunity (herd effect) as if they were "distracting attention from the virus".

For Jean-François Toussaint, " COVID is a disease of the age that shows the evolution of our insufficiencies: cardiac, respiratory, renal, neuronal, etc.. The virus attacks an immune deficiency that makes elderly people unable to defend themselves against it. ». He goes on to say: " COVID-19 is not a juvenile disease at all. It is a mistake to say that children are healthy but highly contagious carriers. Children are only minimally affected by this virus, compared to The role of young people in the configuration of herd immunity will be essential in the next stage, once they are out of other childhood viral diseases such as chickenpox; they are very little carriers and would be almost protective. This hypothesis should be tested. In all populations with a large proportion of young people, it is very unlikely that we will see explosions comparable to those in Italy or Spain, where the tragedy is occurring mainly in EHPADs and retirement homes that are sometimes abandoned". He adds: " In the suburbs, young people frankly don't appreciate confinement. It's not our disease, they say. We're not sick. They're not completely wrong: COVID-19 is not a problem for them right now! But their role in the configuration of group immunity will then be essential. This is the goal of the next stage, once they are out of containment."

Africa could be spared

Could the age pyramid in Africa be a protective factor that would explain the very low intensity of the epidemic in this continent?

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There probably won't be an explosion in Africa. advances Jean-François Toussaint. Since January, the virus has certainly already passed over this continent several times, but it has not found its niche there. It finds its favourite terrain in European countries or in the United States, because of the very large number of elderly people"..

At the time of writing, there are 2239 contaminated cases and 64 deaths in Africa. On a strict statistical level, the continent does not seem to be concerned, even if, for Jean-François Toussaint, " he may only be at the beginning of a possible evolution. If there is an African epidemic, it started towards the end of February, with an extremely low rate of progression. At the same time, Italy was accumulating 20,000 contaminations and 1,400 deaths, for a population 20 times smaller than that of the United States."

These discrepancies can be seen as a result of the very strong competition between viruses in Ecuador and the Tropics. But two other possible reasons can also be found, enlightened by demographic and geographical tropism. First, because the African population is much younger and does not fall within the coronavirus' preferred targets. Professor Toussaint dares " Covid-19 has suddenly become a disease of old Europeans; perhaps that is why its noise paralyses us, while African diseases (malaria, HIV, ...) continue at a very different pace.. The old European rediscovers the face of death, while the wise African never ceased to observe it. "

The second reason is still geography: below 25° North latitude, the coronavirus is very little contaminating and even less lethal. Would there be a geographical optimum only? Or an associated thermal optimum? We don't know yet, but the epidemic phase that will now take place in India will tell us very quickly.

Profile, speed and peak

One of the most striking results of Irmes' work concerns the pattern of spread of the coronavirus. No matter which country is affected, no matter when it emerges, the virus follows exactly the same dynamics. « When we look at all the regions of China outside Hubei and Wuhan, at the heart of the epidemic, we see that the peak of the epidemic is always reached in 4 weeks. Only Korea has managed to achieve an exceptional duration of 3 weeks, without going through containment.. . . ." observes the researcher.

He explains that there is no common measure between an Iranian health system and a Spanish or French health system. And yet, the virus passed its peak everywhere after 4 weeks. Exactly as the other 30 provinces in China did. Italy past their peak on Saturday, March 21st. « In all the countries where both peak and trough are observed, the rise time of 3 to 4 weeks is almost the same. The peak can thus be expected at the beginning of next week in France and at the beginning of April in Spain. ".

Accelerations in the number of deaths in different countries. Source IRMES and Johns Hopkins CSSE 23/3/20

This dynamic profile of the virus, which is always the same everywhere, does not rule out fundamental differences, particularly those concerning the number of victims. Spain has a much higher growth rate than France, no doubt due to its "reservoir" of elderly people and its unfavourable age pyramid. The pace of the epidemic in Spain is the same as in other countries, but the death rate will be very high and the toll will probably be higher than in Italy.

The coronavirus is a sprinter, not a marathon runner...

This coronavirus is a sprinter, not a marathoner. " says Professor Toussaint. Like some other coronaviruses, the newcomer has short expansion times and a speed of spread that is not that of tuberculosis, or Ebola. For the current coronavirus it's in weeks; with Ebola it's several months and a year and a half for the duration of the last outbreak.

The coronavirus that terrorizes the world rises in three to four weeks, then falls back down in a month and vanishes. " But if it goes out, would like to point out Professor Toussaint, It is known to remain present, carried by many animals, bats, pangolins, and other intermediate hosts not yet known. Successive random mutations, proposed by living organisms, eventually broaden human-virus-animal interactions and lead to a new pandemic. A cousin virus may appear in seven or fifteen years, which will find one of the other cracks in our armour. »

This scenario is unpredictable. As much as we can conceive of the general mechanism, we cannot predict when it will occur, nor, above all, what the responsible mutation will be. We are in the stochastic, absolute randomness, the living constantly proposing all possible options.

Professor Toussaint's work can help us to better understand the logic of how this virus works, its own dynamics and physiology. His understanding could enable us to learn lessons from this epidemic, validate the different options taken by States to protect us and, perhaps, understand its risk in order to better control it.

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2 années

I have already read other articles by Jean-François Toussaint. He has the merit of documenting and analyzing what Raoult says, but above all he takes us out of the "narrative" that flooded this sanitary episode; this narrative that says everything and its opposite and that is taken for the truth. His mirroring of the old European and the wise African is so true. One is afraid, the other is wise. One has abandoned his gods and is alone in the face of death; the other knows death because he still lives with it every day....
Thank you!
Michel Manon

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