Why do some patients COVID-19 develop long-term symptoms and others don't? There is still no concrete answer to this question. About 20% of diagnosed patients and about 5% of all people infected with SARS-CoV-2 develop persistent symptoms, the so-called ongoing Covid.
The Symptoms They can include fatigue, post-exercise malaise and cognitive impairment and can affect multiple organs. Although previous studies have shown that people with the so-called long Covid They show signs of immune deficiency, persistent activation of immune cells and production of autoimmune antibodies, the cause is not precisely known and the diagnostic biomarkers are not correctly defined.
Since there is currently a lack of effective treatment, a scientific team conducted a study of the blood serum of 113 patients. Some of them had fully recovered and others suffered from persistent Covid-19 disease, using a healthy control group as a reference.
Of all the patients we followed up to a year after their first SARS-CoV-2 infection, 40 had persistent Covid disease at the six-month follow-up
Thanks to high-throughput proteomic technologies, they measured the serum levels of 6,596 human proteins among the participants. They also observed patients with confirmed acute Covid-19 disease for up to a year and took another blood serum sample after 6 and 12 months. The results will be published in the journal Science.
“Of all the patients we observed up to a year after their first SARS-CoV-2 infection, 40 had persistent Covid disease at the 6-month follow-up.” These and 39 other healthy control subjects were analyzed in detail, with: “More than 7,000 proteins were measured in the blood at several points in time,” he explains to SINC. Carlo Cervia Haslerfrom the Department of Immunology at the University Hospital of Zurich (Switzerland), who is leading the study.
We found blood markers of tissue injury, including red blood cells, platelets and blood vessels
Analysis of these proteins showed that a part of the immune system, called Complement system and whose main task is to eliminate pathogens, has been activated in persistent Covid patients. In healthy people, the complement system fights infections and eliminates damaged cells from the body. However, if it does not return to its default state after an infection but remains activated, it can also damage healthy cells in the body.
“After observing an overly active complement system in patients with persistent Covid disease, we looked for possible damage that could be caused by this system. In fact, we found blood markers of tissue injury, including red blood cells, platelets and blood vessels,” explains the researcher.
The study highlights possible diagnostic biomarkers and treatment information. /AdobeStock
Biomarkers for diagnosis and treatment
There were patients with persistent Covid disease Changes in blood serum proteinswhich suggests to researchers that they are suffering from ongoing thromboinflammatory reactions.
“This study identifies potential biomarkers for diagnosis long Covid and could provide information about treatment. It is important to confirm these results in other patient cohorts with more individuals and different patients,” adds the researcher.
Wolfram RufScientist at Johannes Gutenberg University (Germany), notes in a related article: “While therapeutic interventions with coagulation and complement system inhibitors in acute Covid have had mixed results, their specific pathological features suggest possible interventions for testing clinics.”
This study identifies possible biomarkers for the diagnosis of Long Covid and could provide clues for treatment. It is important to confirm these results in other patient cohorts with more individuals and diverse patients.
For his part, Cervia-Hasler emphasizes: “This novel mechanism has different effects. On the one hand, it contributes to the scientific understanding of this disease and supports further research into the biological mechanisms underlying this clinical syndrome. In addition, we were able to diagnose persistent Covid syndrome in patients with active disease six months after the first SARS-CoV-2 infection. “Because these patients often face psychiatric stigma, objective blood testing is urgently needed to ensure optimal care.”
Finally, the work provides a basis for further investigation of treatments that target the signaling pathways that have been observed to be overly active in people affected by this type of long-term Covid. “New effective treatment methods are urgently needed,” the expert concludes.
Now the research group is asking another set of questions that need to be clarified in future studies, such as whether these treatments against long Covid and whether they are safe or which patients will benefit most from them at what point in the course of the disease.
Reference:
Carlo Cervia-Hasler et al. “Persistent complement dysregulation with signs of thromboinflammation in active Long Covid.” Science
