Science

Covid a long time ago: a few clues on the table, but still a mystery – Sciences et Avenir

Chronic fatigue, shortness of breath, brain fog… In the months after contracting Covid-19, millions of people suffer from “long Covid”, and studies have not yet been able to accurately explain this phenomenon, even if several assumptions are correct. on the table.

According to the US-based Institute for Health Metrics and Evaluation, 145 million people worldwide were affected by long-term Covid in 2020 and 2021. “At least 17 million Europeans,” according to a recent World Health Organization (WHO) estimate.

This will account for 10 to 20% of people infected with the virus.

Fatigue, coughing, shortness of breath, intermittent fever, loss of taste or smell, difficulty concentrating, depression… prolonged Covid presents with one or more of a long list of symptoms, usually within three months of infection and persists for at least two months. The syndrome affects twice as many women as men.

“There are no symptoms really characteristic of long-term Covid, but they still have certain characteristics: they fluctuate with fatigue that remains in the background, they seem to worsen after intellectual or physical effort and become rare over time,” concludes Russian salad. Robineau, infectious disease specialist at Tourcoing Hospital Center and long-term Covid coordinator at the National Agency for Emerging Infectious Diseases.

– Virus reservoirs –

Many teams around the world are working to understand the causes of these symptoms. In France, for example, the Hôtel-Dieu (AP-HP), the University of Paris and Inserm started a long-term Covid study in the “ComPaRe” cohort at the end of 2020 (https://compare.app.fr/covid-long/): “The 2,500 patients are under very regular follow-up, which should allow us to understand the changes in disease manifestations over time,” explains Dr. Viet-Thi Tran, co-investigator of the group.

Long-term Covid presents with one or more of a long list of symptoms, usually within three months of infection and lasting at least two months (AFP/Archive – Ronnie Hartmann).

But the variability of symptoms and their non-specific nature makes research difficult. So far, scientists are exploring several hypotheses.

One of them is the persistence of the virus in the body in certain individuals. So, in early September, a study published in Clinical Infectious Diseases concluded that the Spike protein (the key that allows SARS-Cov 2 to enter cells, ed.) is present in patients with long-term Covid. This suggests viral replication or persistence of viral remnants long after the initial infection.

Live virus or remnants of the virus may support inflammatory activity, possibly at the origin of symptoms.

However, these results were not found by other teams.

There are other directions as well. The virus would disappear after infection, but the initial inflammation once caused would cause the immune system to malfunction.

– Multidisciplinary course –

The hypothesis of the so-called “tissue damage” points to the role of the initial infectious episode in the appearance of persistent lesions in certain organs.

Studies have also demonstrated damage to blood vessels as a result of infection.

“For each of these hypotheses, the data is not yet very reliable,” says Olivier Robineau, betting that “we will not find a single reason to explain the prolonged Covid.” “The reasons cannot be exclusive, they can be related, even change each other for the same person and be different for different people,” he says.

Therefore, it is difficult to find a solution for these long-term Covid patients.

At the Hôtel-Dieu in Paris, a protocol called “CASPER” offers patients a half-day course of treatment throughout the year: “They meet with an infectious disease specialist or internist, a psychiatrist, and then a sports rehabilitation doctor.” explains Professor Bridget Rank, specialist in internal medicine, the origin of this chain.

“In the team’s experience, most of the symptoms can be attributed to + functional somatic disorders + (symptoms result from an imbalance in the functioning of the central nervous system, approx. ed.). As a result, cognitive-behavioral treatment is often associated with controlled physical activity.”

“Patients are called back after three months: most of them are better, more than half say they are cured,” explains Professor Rank. “But about 15% don’t improve at all,” she admits.

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