Leonard Jason: The key to demystifying long COVID-19 could come from studying another chronic condition
There is growing evidence of multiple similarities between patients with long COVID-19 and patients with myalgic encephalomyelitis/chronic fatigue syndrome.
Before the COVID-19 pandemic, 1.5 million people in the U.S. were estimated to have myalgic encephalomyelitis/chronic fatigue syndrome, or ME/CFS, with an annual economic impact of $36 billion to $51 billion. Due to COVID-19, the total ME/CFS prevalence could rise to between 5 million and 9 million people. This would cause the annual U.S. economic impact to rise to $149 billion to $362 billion in medical expenses and lost income.
Certainly, we need to study ME/CFS to find ways of reducing this medical and economic harm. Yet, few funds have been devoted to ME/CFS. In contrast, more than $1 billion dollars has been allocated to the study of COVID-19 in the U.S. Reluctance to fund ME/CFS research might be due to there being multiple potential causes of the syndrome and that it is more scientifically justified to focus research on an illness such as COVID-19 that has clear viral cause.
However, what might be considered a limiting factor in studying ME/CFS could actually provide scientists a window into understanding long COVID-19. There is growing evidence of multiple similarities between patients with long COVID-19 and patients with ME/CFS (who have tested negative for COVID-19).
As an example, cardiac “preload failure” is found in long COVID-19 and ME/CFS. This condition is the inability to provide enough blood to fill the heart properly, which reduces cardiac output and the amount of blood provided to the muscles during exercise. In addition, physiological similarities between long COVID-19 and ME/CFS could signify cerebral neuroinflammation.
Those with COVID-19 have been exposed to the coronavirus, whereas those with ME/CFS have a variety of triggers, including the virus that causes mononucleosis. We all can agree that there are some differences in symptoms of these two illnesses, such as those with ME/CFS do not have the hair loss that can occur with long COVID-19. We can also agree that although one infection triggers COVID-19 illness, it might not be the reason for what maintains a long-haul illness.
So if the majority of symptoms and abnormalities of long COVID-19 and ME/CFS are comparable, it is unlikely that one trigger — the coronavirus — is maintaining the debilitating symptoms of long COVID-19. In other words, we might learn that long COVID-19 is an organism’s response to the triggering event rather than just one virus.
Long COVID-19 patients have been sick for just a few months or a few years. In contrast, the ME/CFS patients have been sick for longer periods of time. If the outcomes of long COVID-19 and ME/CFS are comparable, then studying ME/CFS might allow us to make predictions for those with long COVID-19. Such information could provide critical answers to questions about prognosis.
Finally, with long COVID-19, there is evidence that the initial coronavirus infection reactivates latent viruses such as the Epstein-Barr virus, which has been linked to many other illnesses including mononucleosis. Of interest, 60% of patients with ME/CFS report infectious illnesses before the onset of ME/CFS; the most frequently reported infectious illness is mononucleosis. By studying those who test negative for the coronavirus but have ME/CFS, we could have a better understanding of the relationship of Epstein-Barr virus to both long COVID-19 and ME/CFS (just as Epstein-Barr virus has been related to cancers and multiple sclerosis).
The pandemic has provided the impetus for thousands of scientists around the world to better understand the pathophysiology of COVID-19. The National Institutes of Health RECOVER study is currently recruiting more than 17,000 participants in its national long COVID-19 study, and our committee feels that including people with ME/CFS, who do not have long COVID-19, in research as a comparison group is crucial to furthering our understanding of long COVID-19 and ME/CFS.
Multiple ME/CFS and long COVID-19 patient organizations also strongly feel these comparisons will help us more accurately identify traits and achieve better treatments.
Leonard Jason, Ph.D., and physicians Hector Bonilla, Monica Verduzco Gutierrez and Benjamin Natelson are part of the diagnostics testing and test algorithms subcommittee of the National Institutes of Health’s RECOVER Commonalities with Other Post Viral Syndromes Task Force.
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