On March 17, 2020 at noon precisely, France was confined for the first time. Announced by Emmanuel Macron in a historic television address, the measure will remain as one of the key dates of the COVVI-19 crisis. Previously distant, unreal, even anecdotal or false for some, the health reality has imposed itself suddenly to all French people. Like a warning stroke, addressed to the whole country.
Since this traumatic date, many puzzles have been resolved. Scientists now know how SARS-COV-2 is transmitted, how it infects our cells. Thanks to vaccines, we also know how to protect ourselves from this disease, formerly unknown. But clinically, a mystery is resistant, again and again. Five years later, no one really knows the mechanisms involved in the Long Cavid, this series of strange symptoms that persist in some patients.
The data on the subject have however greatly evolved, since 2020. Thousands of scientific articles have been produced on the issue. Without entirely lifting the veil, they allow a finer understanding of the mechanisms at stake. Above all, they made it possible to confirm the very existence of this pathology. At the start of the health crisis, many doctors thought that patients were not really affected, that they were delusional, or that they suffered from an evil unrelated to their infection. Doubt is no longer allowed.
Something is happening, but what?
There is now a scientific consensus to say that a COVVI-19 infection can trigger a persistent degradation of certain faculties. Patients then describe great fatigue, concentration or mood disorders, respiratory discomfort, difficulties in effort but also a whole series of more singular difficulties, ranging from digestive disorders to skin problems. A burden which, for some, prevents any professional activity.
The affection is very real, yes, but what happens? Even today, scientists ignore it. The body remains, on this subject, a black box. “We know that the virus can remain, especially in the brain. But we still do not know very well what produces the symptoms, and their links between them,” sums up Yazdan Yazdanpanah, infectiologist and director of the National Research Agency on emerging infectious diseases (ANRS MIE).
In October 2024, the institution organized a day focused on this disease, with public health France, and the High Authority for Health. A summary of scientific literature was published on this occasion. Not a week goes by without a study comes out on the long covid, and yet the findings have not really changed since. “What is a problem for us is that we do not have specific tests, organic markers as we say in jargon,” continues the scientist.
How many patients?
Without a reliable diagnostic tool, it is impossible to differentiate patients with covid long from those who suffer from the same symptoms, but with different causes. Result: doubts remain as to the real share of people affected. It would be around 4 % in France, according to studies carried out on adults, and published by Public Health France in 2022. A platform for the sick of patients had to see the light of day to refine these results, but its implementing decrees have still not been published.
In the United States, which retains different criteria to define the Long Cavid, the figures are not at all the same. According to a study published in the journal Infectious Diseases Clinicalin February 2025, from 10 to 26 % of infected people would keep prolonged symptoms. The analysis compares different registers, taken from the Recover project, a gigantic American research program which follows tens of thousands of patients. All of them note the same developments: cases increase when the COVVI-19 circulates; They tend to decrease once the virus is regressing.
The profile of the victims is just as variable. Yes, it is now accepted that vaccinated people are more protected. The patients who have made a serious form are, conversely, more at risk. But, at the same time, women are much more affected than men, in the order of 30 to 45 % more, according to several studiesthe most recent of which appeared in January 2025 in the review Journal of the American Medical Association Network Open. However, they are more rarely admitted to the hospital than infected male subjects.
Not “a” but “long covids?
Faced with as many cases, and as many inconsistencies, scientists are now talking about one, but “long covids. “Several mechanisms would come into account, either separately or in a cumulative way in the body. This means that there are potentially as many strategies to apply. If only one factor is tested, when there are four or five different, the results will necessarily be bad,” said Professor Yazdan Yazdanpanah.
Studies have shown that some patients had abnormal inflammation. Others highlight a Atypical immune response. Others still point to the action of the pieces of the virus that remained blocked in the body, when they do not draw forms of sequelae, such as a damage to lungsblood circulation, or serotonin production. “The key will surely be to combine these approaches in the future,” said the scientist.
So many different processes leave few hopes for the discovery of a single biological marker. On the other hand, a series of indicators could make it possible to establish “signatures” leading to favor one type of long covid or another. In January 2025, researchers published an article in the journal Pediatric Researchof the group Natureshowing that artificial intelligence managed to detect one of these imprints, on around thirty children. These results must be confirmed.
Towards a biological signature?
Yazdan Yazdanpanah calls for the research effort, despite the few advances. Anrs Mie would like to see more French clinical trials emerge, when only one has been launched at the moment. Globally, there are only 61. By comparison, a few months after the first confinement, more than 200 were underway to find a vaccine. “There is also lack of data on children, with whom the longs long is rarer,” alerts the specialist.
This relative low attention to the long covid is partly explained by the absence of emergency: unlike the so -called “acute” covid, long -term conditions do not cause resuscitation stays. On the contrary, they tend to improve over time. But very slowly. Thus, according to the latest French public health study in this area, which already dates from 2022, more than 43 % of patients say they have one two afterwards.
Here, no doubt, it is not a simple “impression”. While they were imperceptible for the patients themselves, cognitive and memory difficulties were identified after the inoculation of Sars-Cov-2 in around thirty English volunteers, in a study published in 2024 in EclinicalMEDICINEa group’s review The Lancet. And this, until a year later. Another analysis, published in Nature Medicine In 2024 showed the same thing on 351 patients already sick. Brain imaging anomalies have also been observed.
The fight of the sick
The idea that the long covid could get out of the imagination of patients, and that there would be nothing to do, has long slowed down the recognition of these sufferings. It is still popular with some general practitioners. “One of the priorities in the future must be to bring communication for health professionals, so that they are up to date on scientific consensus,” calls Daniel Christien, founding member of the main association of COVVID LONG patients, Adition.
Five years later, the association regrets the few means implemented to combat the COVVILE LONG. In January, she sent a open letter To the Minister of Health Delegate, Yannick Neuder, calling for a start, while certain specialized centers have closed in recent months. Unanswered for the moment. “The public authorities often think that the pandemic is over, that it is from the past. But we are still there. And there are many of us, surely millions, according to estimates. There will be no miracle treatment, as we know, but we can get more advances,” continues Daniel Christien.
Accustomed to having to prove their difficulties, patients sometimes fall into the opposite excess: they castigate all the proposals focused on psychological care. However, it is one of the pillars of the care of the Long Cavid. A literature review published in the prestigious review British Medical Journal In September 2024, concluded that it is for the moment the only approach to appease the ills of the patients, with physical rehabilitation.
The deconditioning track
“That we consider that the mind and the brain play a role does not mean that suffering does not exist,” defends Cédric Lemogne, psychiatrist at the Hôtel-Dieu hospital in Paris, often the target of online admonitions. The researcher is convinced that in addition to the “biological” tracks, a mental conditioning can also take place. “Often, amputated people feel strong pain in the member they have lost. There could be similar demonstrations in the case of Long Cavid,” said the specialist.
Him, like several other research teams, have chosen to focus on the persistence of symptomsrather than their origin: “In reality, many patients feel prolonged difficulties after an acute event. This can be the case after gastroenteritis, Crohn’s disease, rheumatoid arthritis, or even Lyme borreliosis. I think there are points in common to all these phenomena, that there is an approach that could make us move forward.”
In each case, a long or not covid, the biological activity of pathogens, when it is measurable, is almost non -existent. “And yet the problems are continuing,” said the researcher. There is, in these reflections, at least an undeniable advance: a long time, the long affections which there is no trace in the organism have been relegated to the margins, reduced or even denied. Thanks to the COVID-19, they too have ended up establishing themselves as a reality on the French.
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