Would we be unequal against the Covid-19? Why does Belgium have a much higher death rate compared to the population than in neighboring countries? What about the African continent, which seems much less affected if we stick to the statistics available? So many questions which question specialists from all over the world, and which concern fields as varied as climatology, genetics, demography and even anthropology.
Understanding the virus better, the way it spreads, its reaction to its environment, identifying the risk factors is essential to manage this global health crisis as effectively as possible.
Because at this stage, certain geographic disparities leave something somewhat dumbfounded. The New York Times recently noted the case of the Dominican Republic and Haiti. The same island, split in two. 8235 cases identified to date in the east, 100 in the west. One example among many.
No need to hope to uncover simple, unique answers. Didier Camus, epidemiologist at the Pasteur Institute in Lille, immediately warns: "There is no clearly identified factor to explain such divergences in prevalence".
The “youngest” countries spared?
This is a proven fact, well known to the French and which partially justified the reopening of schools scheduled for Monday, May 11, 2017: Covid-19 is a disease which affects older people more seriously. In France, according to the latest statistics from Santé Publique France, 91% of the people who died from Covid-19 were aged 65 or over. Young people tend to develop mild forms of the disease, even asymptomatic.
Are the countries least severely affected by Covid-19 those with the youngest populations? If we stick to the cards, there is no doubt that there is a disturbing correspondence between the two criteria. The most telling example remains that of the African continent, where more than 60% of the population is under 25 years of age. Official statistics count around 3600 dead, on this continent populated by 1.3 billion inhabitants. Belgium, with its 11 million inhabitants, has more than double this number. Almost 20% of its population is over 65, while 22% is under 20.
The demographic criterion, however, cannot suffice to explain everything. Japan illustrates this perfectly. Its population is aging, more than a third of the Japanese are over 60 years old. Assessment of the coronavirus since the beginning of the epidemic: 536 dead. "We realize that we have almost no deaths in our countries under the age of 70," notes demographer Jean-Marie Robine, director of research at the National Institute of Health and Medical Research (Inserm). . It is not clear why the elderly are so exposed, but it is. If exceptions like Japan exist, we need to look at the measures that have been taken to stem the epidemic. "
Be careful with the numbers
Exploiting the authorities' figures without questioning their relevance, however, is a challenge. Because if Africa is indeed the youngest continent on the planet, it is also the one in which the measurement of the spread of the virus is the most difficult. Many countries do not test their populations, or only very patchy, despite the numerous efforts made to increase the number of screenings.
Newsletter - The essentials of the news
Every morning, the news seen by Le ParisienI'm registering
Your email address is collected by Le Parisien to allow you to receive our news and commercial offers. Find out more
Specialists are deeply concerned about the lack of visibility as to the health reality on the continent. Several elements call for at least caution, even concern. It took less than a month for almost the entire continent to be affected by the epidemic. If it worsens, the lack of resources could raise fears of a real health tragedy.
A heat-sensitive virus?
"Nobody can believe that the virus has not spread at all in India or Africa", continues Jean-Marie Robine, also an advisor to the management of the National Institute for Demographic Studies (INED) in charge of aging issues. Would the virus develop in less virulent forms in these territories? If the volume of elderly people can be decisive, specialists are working on another factor: the climatic effect.
Professor Mehdi Majdoubi, department head at the Center hospitalier de Valenciennes, is particularly interested in this. “The climatic hypothesis is very serious. Some have unfortunately taken it irresponsibly by claiming that the virus would disappear during the summer. The climatic effects are not yet proven, but one should not wait until the end of the battle to grasp this subject. "
For him, the climate approach does not suffer from any counterexample to date. "We must at all costs keep in mind that this epidemic has a multifactorial character, that the population density in a territory or the policies that have been carried out there, for example, also play a role," he reminds us. But we must not hide the climate issue. The most massive foci are obviously in the northern hemisphere, including on the scale of France ”, he argues.
Less serious forms in the south?
And the specialist to embark on an inventory. “The north of Italy is more affected than the south. It is the same in Spain. In the United States, New York State or Michigan were hit much harder than Florida. In Asia or Africa, it is important not to believe that the virus does not develop, but it would seem that it is in a less serious form. These countries could not hide thousands of deaths. I will cite the example of Brazil, which has suffered an epidemic explosion, but it is a country which has not taken any political decision. "
France, too, would not escape the phenomenon. "Take the Overseas. We have an age pyramid similar to that of the mainland. In Reunion, thousands of tourists arrived in the first half of March. The balance sheet is 500 patients, with no deaths. "
Analysis of the behavior of the virus in the face of climate will take time. If the link was proven, Mehdi Majdoubi considers credible the hypothesis of an inversely epidemic in the coming months, more limited in the northern hemisphere and more in the south in winter. A somewhat nuanced analysis by Didier Dumas. “Everyone said at the beginning that it would calm down when the warm weather arrived. I don't think the virus is that sensitive, at least in our temperate climates. "
The genetic predisposition hypothesis
Specialists do not rule out any leads and some are looking into possible genetic predispositions. Professor Jean-Laurent Casanova, specialist in human genetics of infectious diseases and co-director of the Imagine Institute, is taking a close interest, working specifically on the development of the most serious forms of Covid-19. "Our hypothesis is that this gravity is related to genetic variations, that is to say with a determinism present from birth," he explained recently to La Croix .
Patients are currently recruited in several countries around the world, in particular through the Covid Human genetic effort consortium . The idea is to dissect their genome in order to isolate genetic specificities that can explain the development of the disease in its most serious form. "If we find genetic clues that point to a gene for which a drug has already been developed, then we could simply convert this drug," adds Mark Daly, director of the Helsinki Institute of Molecular Medicine, to the AFP. A long-term job that could take several years.
For Didier Camus, this single genetic criterion also does not explain the very strong variations in the epidemic depending on the country. "These genetic factors, if they exist, concern only a tiny part of the population," he reminds the Parisian. We are talking about very extensive studies, on very small samples. They are much more difficult to conduct than on co-morbidities, such as obesity or diabetes, which seem more obvious. "
Anticipation and the luck factor
Climate, genetics and even demography are far from providing all the answers to the spread of the epidemic. For specialists, there is no doubt that man, through his movements, his way of life, his customs and his political decisions, plays a determining role in the propagation or not of the virus. “Our only weapon is to respect social distancing and hygiene measures, to wear masks, insists Didier Camus. Our means are fragile, but the slightest relaxation is very expensive. "
It is undoubtedly on this point that the populations are the most unequal. In several Asian countries, customs are enough to limit physical contact, from greetings. Past epidemics have instilled, according to many specialists, many reflexes. “I was in Thailand in March, says Mehdi Majdoubi. Travelers' temperatures were taken at airports, medical offices had all set up special windows for those at risk, hydroalcoholic gel was accessible everywhere and the vast majority of the local population wore masks. "
Experienced with epidemic risk, these countries acted very quickly. Massive tests have been implemented, isolation measures have been decided, whether in Singapore, Korea, Japan, Thailand or even Taiwan, to name a few. Examples much closer to us have demonstrated their effectiveness. The Austrian government is breaking popularity records. The deconfinement started in mid-April, the restrictive measures were implemented very early.
Let us cite Greece, again, which decided in mid-February to ban gatherings and confine villages that have welcomed people who have returned from abroad. We could however fear the worst, in this older and more overweight country than the European average. The health crisis is currently controlled. There remain the economic challenges, which could weigh heavily as Greece is dependent on its tourism.
In Africa, many countries have implemented restrictive measures when they had very few cases, also benefiting from a later arrival of the virus.
Late decisions in France?
Jean-Marie Robine does not mince words when it comes to talking about France. “We have repatriated tens of thousands of people from abroad. With what precautions? How many have been tested? He annoys himself. He who works on aging with INED deplores the decisions taken in nursing homes. "The President of the Republic spoke of war , adding that it was necessary to protect the carers as one protects the soldiers. In wartime, civilians are also protected. The staff of the Ehpad were left without material and the elderly were isolated together. The staff were able to transport the virus despite themselves. I do not know if the scientific council did not see or did not alert the executive to the dangers of such a policy. I do not know whether or not the government has chosen to hide them. In any case, there are questions which must necessarily be returned to. "
There remains one last factor. The one that we do not control, which escapes all good will and which can upset the health situation of a country. It is the luck factor, these events which generated a completely uncontrolled spread of the epidemic: a gathering of evangelists in Mulhouse, a football match in Italy, volleyball in Estonia, a spring break in Florida or celebrations near a mausoleum in Iran… So many moments that suggest that yes, we may be unequal in front of the Covid-19.
