Researchers investigating long COVID have found that it may not be based on an immune inflammatory reaction to the disease.
Instead, it may be the case that in these patients, the immune response to COVID-19 may re-trigger other viruses that remain in the body after previous infection, such as human cytomegalovirus and Epstein Barr virus.
In eLife yesterday, Dr Laura Rivino of the University of Bristol, UK, and colleagues state: “Immune abnormalities and inflammation may persist after severe COVID-19.”
They explain that patients frequently report ongoing symptoms for months after recovery. The team assessed 187 samples from 63 patients for immune activation at three and 12 months after infection with mild, moderate, or severe COVID.
Long COVID symptoms were reported by 80% of patients across all levels of disease severity, but were more frequent in patients with severe disease, in line with previous findings.
However, long COVID symptoms were not linked to persistent immune activation specifically to the COVID virus.
They write: “Our study adds to emerging data suggesting that a prolonged immune activation can be observed following COVID-19 which may not directly associate with long COVID.
Dr Rivino said: “Several theories proposed for long COVID include whether it might be triggered by an inflammatory immune response towards the virus that is still persisting in our body, sending our immune system into overdrive or the reactivation of latent viruses such as human cytomegalovirus and Epstein Barr virus.”
A better understanding of inflammation and the immune activation in long COVID “would allow us to understand whether targeting these factors may be a useful therapy for this debilitating condition,” she concluded.
Santopaolo, M. et al. Prolonged T-cell activation and long COVID symptoms independently associate with severe COVID-19 at 3 months. eLife 4 July 2023; doi: 10.7554/eLife.85009
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