Immune differences in long COVID

A research team, funded in part by NIH’s RECOVER Initiative, has found significant differences in the immune cells of individuals with long COVID compared to those without. Many of aspects of the study findings align with previous research into ME/CFS.

The study recruited more than 250 people, comprising of individuals who had been infected by SARS-CoV-2 and those who were uninfected. Amongst those who had been infected, some had developed long COVID, whilst others had not. The researchers measured levels of various immune cells and markers in the participants’ blood, including antibody responses to SARS-CoV-2 and a number of other viruses.

What were the findings?

The team found that, compared with others, individuals with long COVID had:

  • – Higher levels of immune cells, namely non-conventional monocytes and activated B lymphocytes; and lower levels of other immune cells, namely type 1 conventional dendritic cells and central memory T cells
  • – Evidence of strong immune responses against SARS-COV-2 and other viruses, particularly Epstein-Barr virus (EBV) – suggesting recent EBV reactivation

The researchers also used machine learning to identify which features best predict long COVID status. The strongest predictors included much lower cortisol levels, elevated levels of a protein called galectin-1, increased antibodies against EBV, and reduced levels of certain immune cells


The authors believe that these findings could provide valuable insights into the pathophysiology of long COVID and aid in the development of relevant biomarkers. It is worth noting that many themes in this study parallel research into ME/CFS, such as the discussion of viral reactivation, including EBV, which was also addressed in a recent conference upon which we reported.

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