► Why is France choosing to extend the confinement?
The Elysee Palace did not wait for the intervention of Emmanuel Macron Monday April 13 to announce it: as of Wednesday, the President of the Republic announced that the confinement would be extended beyond April 15. Without specifying at this stage nor when or how the French will be able to start being able to leave their home.
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This extension comes when other countries, such as Austria, Denmark and the Czech Republic have already announced a gradual deconfinement of their population. “Yes, but nothing says that in these countries, a new epidemic wave will not intervene. There is really a risk to be defined too soon because in these countries, as in our country, the number of people immunized remains low ”, says Professor Yves Buisson, head of the “Covid-19” cell at the Academy of Medicine.
The same warning was issued by the World Health Organization (WHO) on Friday, April 10. “Lifting restrictions too quickly could lead to a deadly resurgence” of the pandemic, said its managing director, Tedros Adhanom Ghebreyesus.
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Experts advising the Elysee Palace have recommended maintaining containment for two reasons. The first is to avoid any risk of saturation of resuscitation services. It was first and foremost to preserve the ability of hospitals to treat all severe forms of the disease that containment was implemented in mid-March.
Today, we see that the number of new admissions to “sheaf” is certainly declining a little in the Great East and in Ille-de-France. But in these two regions, resuscitation services are still largely over-occupied by “Covid” patients who must remain hospitalized sometimes for two or three weeks, ie an average length of stay much higher than the average.
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If the Elysee Palace has decided to extend the confinement, it is also to allow the circulation of the virus in the population to be reduced as much as possible. Hoping that the dynamics of the epidemic will be less strong when a deconfinement begins, which will necessarily be done in stages. With a question in the form of a puzzle: how to gently raise the collective immunity of the French while avoiding as much as possible the contamination of the elderly and at risk subjects, to avoid any new influx to hospitals?
► What do we know about collective immunity in France?
This is crucial to manage the fight against the epidemic. When Covid-19 arrived in France, no one had ever been infected with this new virus. The entire population was therefore “receptive” and exposed to contamination.
At this point, experts estimated that, on average, an infected individual contaminated on average between 2 to 3 people around him. According to them, the epidemic can only start to ebb when this infected subject transmits to less than one person around him. And this can only happen when at least 60% of the French population is infected and therefore a priori immune.
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A goal still far from being reached given the figures that are currently circulating. After a survey of general practitioners, the MG-France union estimated last week that 1.6 million French people may have been infected.
Other studies all come to the same conclusion: collective immunity does not exceed 10% of the population. “But these figures come from opinion surveys or mathematical modeling and not from evidence. These are mostly predictions that need to be taken with great caution “, says Professor Antoine Flahault, director of the Institute of Global Health at the University of Geneva.
► How is this collective immunity estimated?
Today, most of the data therefore comes from these modeling studies. “With mathematical laws, it is possible to make simulations on the number of infected people in a population”, explains Mircea Sofonea, lecturer in epidemiology and evolution of infectious diseases at the University of Montpellier.
“One of the parameters retained at the outset was the level of mortality from the virus, which we could estimate for example on the Diamond Princess, this boat where we could test all the people on board, he explains. Once we have the death rate, we can look at the number of daily deaths in France to arrive at calculating, after extrapolation, the number of people infected in the population. “
But if these models can give an indication, other tools would be necessary to have a more precise estimate of the number of people having been contaminated in France. Some experts suggest conducting weekly telephone or Internet surveys of a representative sample of the population. *
“The problem is that without having done a serological test to test the antibodies in the serum, it is difficult to know if you were really infected. Many people in recent weeks may have had fever or symptoms suggestive of Covid. But it is not certain that they were infected, or even that they report it during opinion polls “, says Professor Flahault.
According to him, the only way to get the most exact idea possible is to do serological tests on a sample of people representative of the population. “We can test 500 or 1,000 people to see who has antibodies and who doesn’t. It is these field seroprevalence surveys that we are currently conducting in the canton of Geneva ”, says Professor Flahault.
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In France, “A similar study is currently being done in Marseille with blood donors and Inserm will launch a larger study in the general population”, explains Xavier de Lamballerie, virologist at the Timone hospital in Marseille. But today scientists do not know definitively if infected but asymptomatic people are really immune. And nobody knows for how long the antibodies, discovered through serological tests, will be protective against a new infection.
► Should infected people be isolated outside their homes?
This is another idea that has come up strongly with many experts. “Extended confinement is a necessary but not sufficient measure. Today, we see that the vast majority of contaminations are in the immediate environment and in particular family “, underlines Professor Buisson. However, today, the instruction given to anyone tested positive, or having signs very suggestive of Covid, is to stay at home, avoiding contact with loved ones as much as possible.
“But it is far from obvious when you live with others in a small space”, continues Professor Buisson, who, like others, proposes to isolate these infected people outside their homes. “We could group them in hotels that are now almost empty because of the epidemic and keep them away from their loved ones for 14 days. “
This isolation has been widely practiced in China but in an authoritarian manner. “I don’t think that in France, infected people should be forced to go and isolate themselves in these” Covid hotels “. But I think a lot of people would agree with the idea of not putting their spouse or children at risk of infection. “, adds the doctor.