What to remember from a new study that points to a weakened immune system and opens avenues for screening and treatment

Researchers from Zurich (Switzerland) observed abnormalities in proteins associated with the immune response in the patients’ blood.

Four years after its appearance, it is a pathology that is poorly understood. Long Covid, which according to the WHO is estimated to affect about 10 to 20% of patients infected with SARS-CoV-2, may be better diagnosed and treated thanks to the results of a team of researchers from the University and Zurich Hospital. Switzerland). In an article published in the journal Science, Friday January 19, they confirm that this chronic disease is associated with immunodeficiency that leaves traces in the blood, which can facilitate its detection and help provide a response to patients. Franceinfo summarizes what to remember from this study.

A component of the immune system that is disrupted

The work of this Swiss team is based on the analysis of blood serum, that is, the liquid part of the blood, purified from its cells and proteins that participate in its coagulation. The researchers examined the proteins present in the serum of 152 people, 113 of whom were infected with Covid-19. After six months, 40 patients had prolonged symptoms of Covid.

In the latter serum, the scientists observed changes in proteins associated with the complement system, which participates in the immune response and helps our body fight infection. “In patients with prolonged covid, the complement system does not return to resting state as it should”, But remain vigilant, the head of the study, Onur Boymann, explained to the Swiss press agency Keystone-ATS, as quoted by the Swiss daily season.

A possible explanation for the variation in symptoms

The discrepancy observed by researchers is not without consequences: “If the complement system remains active, it attacks healthy cells in various organs and damages or destroys them”explains researcher Onur Boymann, who is also director of the immunology clinic at the University Hospital Zurich.

“We have found another piece of the long Covid puzzle, which also explains why the disease can cause such a variety of symptoms”, the scientist estimates. It manifests itself as cognitive disorders, attention or memory, as well as fatigue. “Patients Talk About Brain Fog”Franceinfo reported Eric Guage, head of the Department of Biophysics and Nuclear Medicine at Marseille University Hospitals. “Heart problems are also possible”He adds.

Pathways to screening and treatment still need to be investigated

Currently, identifying chronic covid is difficult. Symptoms can be confused with other illnesses. The definition adopted by the World Health Organization highlights this difficulty, as it attributes prolonged covid to any symptom that appears within three months after contamination, lasts for at least two months, and has no other explanation. Detection by default due to lack of specific markers for this disease.

If confirmed, the results of the study by researchers at the University of Zurich suggest a more reliable way to identify the disease and distinguish it from other pathologies. However, the screening does not seem easy, because the scientists used a complex method, which cannot be used on a daily basis in hospitals or laboratories, Onur Boyman admits to Keystone-ATS.

The observations from this new study may also point the way to treatment. A Swiss researcher notes that“There are already companies developing complement inhibitors”, drugs that reduce the action of this component of the immune system, which are already used to treat other autoimmune diseases. But the study is inconclusive on their potential effectiveness against Covid in the long term.

Other researchers, who were not involved in the study, urge caution and patience. Professor David Lynn, an immune system expert at Flinders University (Australia), emphasizes that other recent work has highlighted the role of the complement system. “Much work is still needed to understand the different mechanisms put forward in these different studies and, more importantly, to develop new treatments based on these findings.” he warned, quoted by the Science Media Center.

The same source also reports the words of Peter Openshaw, Professor of Experimental Medicine at Imperial College London: “It is important to emphasize that it would be premature to offer new treatments to patients based on these findings, but the study shows how new therapies can be tested in future trials (some of which are already underway).”