Since the appearance of “2019 n-CoV” in China at the end of December, scientists have known a little more about this new virus which is the source of a global health alert triggered by the World Health Organization. But they still lack key elements to predict the evolution of the epidemic and find a cure.
WHAT WE KNOW
This new virus, dubbed "2019 n-CoV", appeared in Wuhan, China, at the end of December, belongs to the family of coronaviruses, known for more than forty years. Its name comes from its envelope, which forms like a coat with a layer of hair, similar to a crown. "There are four human coronaviruses that circulate endemic throughout the year in France," notes Professor Eric Caumes, head of the infectious and tropical diseases department at the Pitié-Salpêtrière hospital in Paris. They give mild colds while the new coronavirus is the equivalent of a big flu. ”
Contagious, this new virus is transmitted much faster than that of the flu. With an assessment which amounted Sunday February 9 to 811 dead in China, one in Hong Kong and one in the Philippines, it is now more deadly than its cousin, severe acute respiratory syndrome (SARS) whose epidemic has killed 800 people in the Middle Empire in 2002-2003 or the Sea, a virus of the same family, detected for the first time in 2012 in Saudi Arabia.
Its low mortality is even falling, according to recent figures: it went from 2 to 3%. In addition, "80% of those who died were elderly and 75% of them suffered from illness," explains Vincent Enouf, deputy head of the National Reference Center for respiratory infection viruses at the Pasteur Institute.
According to a latest assessment , this coronavirus has already affected nearly 37,200 people in China, but the rate of new infections seems to be slowing down (3,900 on Saturday, 2,600 on Sunday). More than 320 other cases have been confirmed in around 30 countries, including 11 in France.
Scientists also know more about the length of the incubation period, which is refined over the days, with an average of 5 to 6 days, even if this period can range from two days minimum to 14 days maximum. We also know how to diagnose it.
WHAT WE STILL IGNORE
"Everything remains to be learned," exclaims Vincent Enouf. We do not know how long it can be detected in someone who is no longer sick. Or if a person can be contagious when they have no symptoms yet. ” This is what the Chinese say. But this point is still debated. "There would be some examples in their country of contamination before the onset of symptoms, but only one to two cases are concerned," recently explained Eric D'Ortenzio, epidemiologist and scientific coordinator at Inserm (National Institute of health and medical research), at a meeting.
There are key elements missing, according to Professor Eric Caumes. "We do not know how the epidemic will progress in China, will we manage to control it and how will it evolve in France", questions the head of the infectious and tropical diseases department at Pitié-Salpêtrière .
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It is also unclear which animal has transmitted the virus to humans. The pangolin, a scales mammal, on the list of endangered species, could be this famous "intermediate host", according to researchers from the University of Agriculture of southern China, who did not give more details.
Finally, doctors still do not have effective treatments. "This is problematic because there are some serious forms that we cannot cure," admits the professor, adding that several drugs are being studied. Researchers are working on a vaccine. But it's impossible to know exactly when this antidote will be found. One thing is certain, not tomorrow. “And perhaps, adds Eric Caumes, that it will be available once the epidemic is over. "