Study reveals possible markers of persistent COVID in blood

Between 5% and 20% of people infected with the virus that causes COVID-19 eventually develop a range of debilitating symptoms that last for months after infection. These cases are known as persistent COVID-19. According to the journal Science, a team of researchers from the University of Zurich has developed a method that allows for unprecedented detailed monitoring of a range of proteins present in human blood. Thanks to this technique, a number of markers have been identified that may be associated with the so-called “long COVID.” This discovery opens up new possibilities for diagnosing and treating this disease.

The study focused on analyzing samples from 113 patients with persistent COVID. Specifically, they tracked a set of more than 6,500 proteins present in blood serum. In some cases, only one sample was analyzed. But for patients with more severe symptoms, samples were taken six months and a year after infection. Analyzing all this information has finally provided some clues to understand the extent to which persistent COVID causes changes in the immune system, which in turn causes a range of symptoms of discomfort and deterioration.

As the authors of this work, led by Carlo Cervia-Hasler, explained, patients with persistent COVID exhibit a number of changes in proteins associated with inflammatory and immune responses. More precisely, everything points to a significant deregulation of the so-called complement system (a set of molecules involved in regulating the immune response of the human body). A possible connection has also been discovered between these mechanisms and the activation of “latent viruses”, such as, for example, varicella-zoster and mononucleosis viruses (cytomegalovirus), as well as the herpes virus (Epstein-Barr). Researchers believe these mechanisms may be responsible for long-lasting COVID symptoms.