ANALYSIS
Why such an epidemic outbreak? A century after Pasteur, how can we today fight covid-19? Science has been mobilizing for several weeks to respond to "one of the most serious health crises of our century" in the words of Emmanuel Macron. Patrick Berche, Professor Emeritus of Microbiology, former director of the Institut Pasteur, and Philippe Sansonetti, Professor Emeritus at the Institut Pasteur and Professor at the Collège de France, were the guests of Europe 1 Sunday, to take a step back on the pandemic.
Epidemiological precedents
"The flu pandemics are relatively comparable to what is happening now," says Patrick Berche, as "the great pandemic of" Spanish flu "of 1918 which killed about 50 million people", or the Asian flu of 1957, 2 million dead, and that of Hong-Kong (1968-9) which spread to Europe, with 1 million deaths worldwide and 40,000 in France according to an a posteriori count.
"But we had no therapeutic arsenal, in particular no antibiotics. Nothing could stop the Spanish flu virus, which ended up disappearing," he recalls. A notable difference confirmed by Philippe Sansonetti: "The flu killed, when it killed at that time in 1918 - and this is still the case among the elderly - by superinfection with bacteria, in particular pneumococcus. . What is more annoying with these emerging viruses that affect the lungs is that they seem to have a capacity for personal destruction, not necessarily requiring microbial superinfection ".
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Learn from the past
Today, all that has changed, but lessons can still be learned: one of the peculiarities of the "Spanish flu", recalls moreover Patrick Berche, "is that it killed young people, between 20 and 40. Which is probably linked to the epidemiological conditions of the war of 14-18: there were camps, people stationed in constant gatherings, transfers by boat across Europe of almost 2 million of American soldiers ... So this flu, born in the United States, was transmitted to Europe and to the whole world with an incredible speed - whereas there was no plane at the time! "
Hence the importance of respecting measures to avoid gatherings, and the famous "barrier gestures". The professor of microbiology also considers "interesting" the example of the Asian flu "because there is a precedent of a health system which collapses! For eight days, there was no more possibility of hospitalization because the caregivers were sick. We must remember this historic episode: preserve the health system, take precautions so that we do not arrive at a time when we can no longer hospitalize because there is no longer caregivers! "
Can we fight the virus other than by isolation?
"Therapeutics are not yet available, unless we can reposition existing antiviral molecules. [...] As the vaccine is specific to each microorganism, we cannot find, test and regulate a vaccine in a few days or weeks ", explains Philippe Sansonetti. "We have to speed up the procedures but today, we can especially count on isolation above all. And it has to be extremely strict." "We have a few molecules that work on SARS, 70% cousin to the current virus. [...] But it will take at least 1 or 2 years before having an effective vaccine," adds Patrick Berche.
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Will the microbe always be faster than humans? "Man is still faster and faster," timed Philippe Sansonetti. "It took several months or even years to identify the AIDS virus. When the epidemic began in China, it took only a few days to identify the virus and set up diagnostic tests! With progress molecular biology, sequencing, we can detect an emerging virus, without exaggerating, in a few hours, which was not the case 30 years ago ".
According to the two Professors, finally, Italy being the image of France with a week in advance, "it is only physical barriers, avoidance, hand washing, which can reduce the spread. "So far, there is not much more brilliant to offer. If the epidemic continues at this rate, we risk having far more drastic measures to isolate people."