Question

I’ve been reading some interesting new research which indicates that reactivation of viruses that lay dormant in the body after the initial infection could be a cause of Long Covid. The reasoning seems to be that Covid infection activates the body’s immune system and this results in the reactivation of viruses that have been lying dormant and harmless in the body but now become active again and are capable of causing symptoms. Given the overlaps between Long Covid and ME could this be happening here as well? And has any research been done into this in ME?

Answer

I suspect you are referring to the research that has examined the possible role of reactivated Epstein Barr Virus (EBV) infection in people with Long Covid that hailed from two recent studies (1,2). As you correctly point out, these viruses could be playing a role in causing some of the symptoms that persist in Long Covid.

Epstein Barr Virus (EBV) is the infection that causes Glandular Fever which is perhaps the most common trigger for developing prolonged post-viral fatigue leading to a diagnosis of ME/CFS. EBV belongs to a family of viruses called human herpes viruses – where it is classified as HHV-4. All these viruses can lay dormant after the initial infection but then reactivate in later life to cause other health problems.

Cytomegalovirus (CMV), Epstein Barr virus (EBV) and Varicella-zoster Virus (VZV) are the most common herpesviruses often acquired in childhood. They establish persistent, latent infection and are likely to impact the developing immune system. In childhood, VZV causes chickenpox but CMV and EBV infections are usually asymptomatic. If acquired in adolescence, EBV can cause glandular fever. VZV can reactivate and cause shingles in later life.

As far as ME/CFS is concerned, this observation is nothing new and quite a lot of research has been carried out over the years into the role of reactivated viral infection, especially with human herpes virus infections. However, the results have not always been consistent. The ME Biobank, which is funded by the ME Association, has done a lot of this research. They published results that indicate looking for evidence of a past immune response to different human herpes virus infections can help to sub-group people with ME/CFS (3).

If this type of research is able to conclude in the future that reactivated viral infections do play a central role in causing and perpetuating both Long Covid and ME/CFS, then it would support the need for clinical trials to assess the use of e.g., antiviral drug treatments. It also raises the question of whether we should be developing a vaccine to prevent some of these infections, especially EBV, which might not help people who have ME/CFS now, but could help prevent people from getting it in the future.

References:
1: Chen T et al. Positive Epstein Barr virus detection in coronavirus disease 2019 (COVID-19) patients. Scientific Report, 2021; 11: 10902. Published online 2021, May 25.

2: Gold JE et al. Investigation of Long COVID Prevalence and Its Relationship to Epstein-Barr Virus Reactivation. Pathogens 2021 Jun; 10(6): 763. Published online 2021, Jun 17.

3: Domingues TD et al. Herpes viruses Serology Distinguishes Different Subgroups of Patients From the United Kingdom Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Biobank. Frontiers in Medicine Med 2021, July 5.