Fatigue, effortless shortness of breath, persistent cough, chest pain, headache, dizziness, skin, eye or digestive problems… The list of symptoms persisting for several weeks after SARS-CoV-2 infection is long and is not the prerogative of this virus.
Indeed, more than a disease, some specialists see it as a classic post-infectious syndrome with strong similarities to post-poliomyelitis, chikungunya, dengue or Lyme disease symptoms.
But what about its causes? Several hypotheses have already been studied: specific composition of the microbiota, reservoir of the virus in the intestineand lately, dysregulation of part of the innate immune defense.
This is the subject of research by scientists from Inserm and Montpellier University Hospital, the results of which have been published in the Journal of medical virology.
A defense mechanism
The researchers relied in particular on the results of previous work, showing that in patients with severe forms of Covid-19, “the formation of NETs is (…) amplified”.
What is it about ? Of « neutrophil extracellular traps » which is translated as “neutrophil extracellular traps”. This defense mechanism is capable of trapping and destroying extracellular pathogens such as viruses, but also, in some cases, of « trigger excessive inflammationdeleterious to the body..
Are these NETs still present in the body several months after infection with SARS-CoV-2? Yes, answer the researchers, who analyzed the post-acute infection assessments of more than a hundred Covid patients, carried out at least six months after their release from the critical care unit.
Scientists have also noted the persistence ofautoantibodies produced by the immune system, and associated with “abnormal formation of clots in the veins (phlebitis) and in the arteries (arterial thrombosis)”.
Thus, the researchers conclude, “the amplified and uncontrolled production of NETs six months after infection as well as the persistent presence of auto-antibodies could partly explain the symptoms of long Covid, in particular via the formation of micro-thromboses ».
This track of the dysregulation of the immune response must however be confirmed by other research. Work is already underway.