Endothelial Dysfunction in Post-infection Fatigue Syndromes

Inclusion Criteria: The inclusion criteria for ME/CFS patients not infected with SARS-CoV-2 (n=17; females: 70.59%; age (years): 40.10 ± 10.80) and Long-Covid patients (n=30; females: 73.4%; age (years): 37.70 ± 9.96) include profound fatigue and at least one of the following symptoms: PEM, autonomic dysfunction, and/or orthostatic intolerance. All participants were included only if they were at least 12 weeks past an acute EBV infection and/or 10 weeks past an acute SARS-CoV-2 infection, respectively. SARS-CoV-2 specific IgA (A) and IgG (B) antibody titers were measured using commercial test kits (Anti-SARS-CoV-2-ELISA (IgA) and Anti-SARS-CoV-2-QuantiVac-ELISA (IgG); Euroimmun, Germany) in plasma samples. Exclusion Criteria: Participants' exclusion criteria included evidence of acute malignant diseases, diabetes mellitus, acute sepsis, chronic inflammatory gastrointestinal diseases, and frequent intake of analgesics, antacids, or antibiotics. Furthermore, no previously hospitalized SARS-CoV-2 patients were included, eliminating false-positive fatigue due to intensive care treatment, such as artificial respiration.