Covid long: tracks and mystery

Chronic fatigue, shortness of breath, “brain fog”… Several months following their infection with Covid-19, millions of people suffer from a “long Covid”. A phenomenon that research has not yet been able to precisely explain; but hypotheses exist. According to the Institute for Health Metrics and Evaluation (USA), 145 million people worldwide suffered from long Covid in 2020 and 2021. “At least 17 million Europeans”, according to a recent estimate of the World Health Organization (WHO). This would represent between 10 and 20% of people who have been infected with the virus, says AFP. Fatigue, cough, shortness of breath, intermittent fever, loss of taste or smell, difficulty concentrating, depression… the long Covid is manifested by one or more symptoms from a long list, generally within three months following infection and persisting for at least two months. The syndrome affects twice as many women as men, note the researchers. “There are no symptoms really specific to “long Covid”, but they still have certain characteristics. Thus, they are fluctuating with a fatigue that remains in the background. They seem to be exacerbated following intellectual or physical effort and become rarer over time”, summarizes Olivier Robineau, infectious disease specialist at the Tourcoing hospital center and coordinator on “Covid long” at the ANRS ǀ MIE, in the “Viral reservoirs” sector “. Many scientific teams are working around the world to understand the causes of these symptoms. In France, for example, the Hôtel-Dieu hospital (AP-HP), the University of Paris and Inserm launched, at the end of 2020, a study on the “long Covid” within the cohort “ Compare”. “2,500 patients are followed very regularly, which should enable us to understand the variations in the manifestations of the disease over time”, explains Dr. Viet-Thi Tran, co-investigator of the cohort. However, the variability of the symptoms and their non-specific nature make research difficult. So far, several hypotheses are being studied by scientists. One of them is the persistence of the virus in the body in some people. Thus, at the beginning of September, a study published in the journal Clinical infectious diseases concluded that the Spike protein was present. [la clé permettant au Sars-Cov 2 de pénétrer dans les cellules, ndlr] in people with long Covid. This suggests viral replication or the persistence of viral remnants long following the initial infection, underlines AFP A live virus or remnants of virus might maintain inflammatory activity, perhaps at the origin of the symptoms. However, these results are not found by other teams. Other avenues exist. The virus would have disappeared following the infection, but the initial inflammation, once triggered, would have caused a disruption of the immune system. The so-called “tissue damage” hypothesis evokes the role of the initial infectious episode in the appearance of lasting lesions in certain organs. “For each of these hypotheses, the data is not yet very solid,” says Olivier Robineau. The researcher is betting that we will not “find a single cause to explain the long Covid”. “The causes may not be exclusive, they might be associated, or even follow each other in the same individual and be different in different individuals,” he explains. It is difficult today to find a solution for these people with a “long Covid”. At the Hôtel-Dieu (AP-HP) in Paris, a so-called “CASPER” protocol has been offering patients a course of care for a half-day for the past year. “They meet an infectiologist or an internist, a psychiatrist and then a doctor specializing in sports rehabilitation”, explains Pre Brigitte Ranque, specialist in internal medicine, at the origin of this course of care. dedicated. “The patients are called back three months later: the majority of them are better, more than half say they are cured”, explains Pre Ranque. The fact remains that 15% of people do not see any improvement in their situation, despite this circuit.