Long Covid is the long-term consequence of an acute infection with . A long and debilitating disease, it is difficult for doctors to diagnose due to the great diversity of experienced by patients. The scientific community is looking for biomarkers that can make it easier for doctors to identify people with prolonged Covid. A research team at Boston Hospital in Massachusetts studied the persistence of of in people still affected by at least four weeks after the initial infection.
Circulating antigens, in the blood of people with long Covid
and carried out on a small group of volunteers (63 volunteers), some of whom diagnosed with “long Covid”, detected fragments of the S protein (the 1), all protein S, protein N (the nucleocapsid) in the plasma of the participants. The follow-up lasted 12 months and in 65% of the patients one of the three antigens was identified at some point during the follow-up; being the whole protein S the most frequent antigen. In patients who have but not , these circulating antigens are absent. By themselves, these results are not strong enough to say that circulating antigens of the they are not a reliable marker to diagnose the entire population, nor that they have any implication in the symptoms of prolonged Covid.
Still a long search
But the clues pile up. They come from independent studies, often modest, and point in the same direction: the coronavirus could persist as an active reservoir in various organs of the human body. the presence of coronavirus RNA in respiratory and cardiac tissues and in the intestines up to 230 days after the onset of symptoms. In children, the called MISC or PIMS, is due in part to an alteration of the intestinal barrier by the . In this case, pockets of active virus also form in the intestines and release viral antigens into the bloodstream. The coronavirus also seems to unbalance the intestinal flora in people with long-term Covid.
the appear as an important organ in the etiology of the long Covid. Despite these consistent observations, no study to date has accurately demonstrated the origin(s) of prolonged Covid. Viral reservoirs in the body, persistent antigens, but also There are three factors that are considered to be involved in prolonged Covid, the causal link between its presence and symptoms remains to be demonstrated.