Long COVID not caused by COVID-19 immune inflammatory response, new research finds

severe symptoms displayed significant dysfunction in their T-cell profiles indicating that inflammation may persist for months even after they have recovered from the virus. Reassuringly, results showed that even in severe cases inflammation in these patients resolved in time. At 12 months, both the immune profiles and inflammatory levels of patients with severe disease were similar to those of mild and moderate patients.

Patients with severe COVID-19 were found to display a higher number of long COVID symptoms compared to mild and moderate patients. However, further analysis by the team revealed no direct association between long COVID symptoms and immune inflammatory responses, for the markers that were measured, in any of the patients after adjusting for age, sex and disease severity.

Importantly, there was no rapid increase in immune cells targeting SARS-CoV-2 at three months, but T-cells targeting the persistent and dormant Cytomegalovirus (CMV)—a common virus that is usually harmless but can stay in your body for life once infected with it— did show an increase at low levels.

This indicates that the prolonged T-cell activation observed at three months in severe patients may not be driven by SARS-CoV-2 but instead may be “bystander driven” i.e. driven by cytokines.

Dr. Rivino added, “Our findings suggest that prolonged immune activation and long COVID may correlate independently with severe COVID-19. Larger studies should be conducted looking at both a larger number of patients, including if possible vaccinated and non-vaccinated COVID-19 patients, and measuring a larger range of markers and cytokines.

“Understanding whether inflammation and immune activation associate with long COVID would allow us to understand whether targeting these factors may be a useful therapy for this debilitating condition.”