The origin of long Covid, a syndrome with still mysterious mechanisms, has perhaps been partly elucidated by British researchers.
The origin of long Covid may have been partly elucidated by researchers at the University of Cambridge in the United Kingdom. In people who, more than six months after being infected with the Covid-19 virus, still feel severe fatigue with sometimes problems with concentration and memory, loss of smell or taste, shortened breathing or headaches, scientists found excess production in the blood of a typical mediator of inflammation, interferon gamma (IFNg). They published their work in the journal Science Advances.
A residual presence of viruses?
This excessive production, which comes from a small fraction of the T8 lymphocytes of the immune system, disappears with post-Covid syndrome. It could be linked to a residual presence of virus which has already been detected in patients with long Covid, a hypothesis reinforced by the fact that vaccination against the Covid-19 virus often reduces symptoms.
Conditions resembling certain symptoms of long Covid
In addition, when used as a drug, IFNg can induce conditions resembling certain symptoms of long Covid, specify the researchers. “However, knowing whether this anomaly is responsible for the manifestations of long Covid remains to be demonstrated”underlines Pierre Corbeau, immunologist at the CNRS Institute of Human Genetics in Montpellier.
Other viral infections such as those caused by other coronaviruses, dengue, Epstein-Barr or influenza viruses can also lead to the persistence of comparable symptoms and could also be explained by an excessive release of IFNg in the blood suggest the researchers.
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