There Is No Established Connection Between Long-COVID and Chronic Fatigue Syndrome

Fatigue is the most common symptom of Long-COVID (LC), characterized by persistent or new symptoms occurring at least three months after the initial SARS-CoV-2 infection, with no other identifiable cause. This study aims to assess the prevalence of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) as a condition associated with LC. The study included 37 adult controls without SARS-CoV-2 infection and 32 cases with a history of infection, categorized into two groups: LC-yes and LC-no. ME/CFS was diagnosed using the International Consensus Criteria. The most frequent symptoms of LC included post-exertional malaise (PEM), neurosensory, perceptual, or motor disturbances, cognitive impairments, sleep disturbances, pain, loss of thermoregulatory stability, and flu-like symptoms, with significant differences compared to the other groups. PEM was reported in all LC-yes cases. ME/CFS was diagnosed in 18.8% of the LC-yes group, 6.7% of the LC-no group, and 10.8% of controls, with no significant differences. Experiencing more than six symptoms during acute infection—such as tiredness, loss of taste, fatigue, loss of smell, headache, fever, cough, myalgia, sore throat, dyspnea, rhinorrhea, and diarrhea—doubled the likelihood of developing LC. Experiencing at least six symptoms during the acute infection further increased the likelihood of developing LC. A high proportion of LC cases exhibited PEM, neurosensory, perceptual, or motor disturbances, cognitive impairments, and sleep disturbances, with significant differences compared to the control and LC-no groups. However, only 18.8% of LC cases met the ICC criteria for ME/CFS diagnosis, showing no significant difference from the LC-no and control groups.