On the Prevalence of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome after a SARS-CoV-2 infection

There is an increasing body of evidence connecting the post-acute SARS-CoV-2 condition (PASC, commonly known as long COVID) to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), a debilitating disease of unknown cause characterized by persistent and unexplained fatigue, post-exertional malaise (PEM), among other symptoms.^1,2 This connection implies that, in the clinic, some PASC cases comply with the official case definitions of ME/CFS. As such, there is a necessity to quantify the burden of ME/CFS among the PASC population in order to delineate effective healthcare interventions for the benefit of these patients who are often neglected or, in some extreme cases, stigmatized by medical staff and society.

To answer this urgent research question, Dehlia and Guthridge⁴ performed a systematic review and meta-analysis of recent data on PASC adults and reported an ME/CFS prevalence estimate of 51% (95% CI, 42%-60%); this systematic review and meta-analysis will be referred to as PASC-ME/CFS study. In the present Letter to Editor, we aimed to discuss the reliability of this estimate using the research protocol from the European Network on ME/CFS (EUROMENE) for systematic reviews and meta-analysis on the epidemiology burden of ME/CFS in Europe.^5,6