Blood-Brain Barrier Integrity and Immune Dynamics in Neuropsychiatric Sequelae of Post-SARS-CoV-2 Onset ME/CFS Versus Pre-Pandemic ME/CFS Patients

Inclusion Criteria: * Inclusion criteria for pre-pandemic onset ME/CFS cohort: * 18-70 years of age * At least 8th grade education * Onset of the following symptoms prior to July 2019 (Pre-SARS-CoV-2 pandemic) and meeting 2015 IOM diagnostic criteria for MECFS: * Substantial reduction in functioning and persistent and profound fatigue for at least 6 months. The person is unable to undertake the same level of activity before they became - . Their fatigue is not the result of significant exertion and is not substantially alleviated by rest. * Post-exertional malaise. * Unrefreshing sleep * At least one of the following two symptoms: * Cognitive impairment (difficulty with memory, finding words, understanding etc). * Orthostatic intolerance (symptoms like palpitations, sweating, dizziness, nausea when standing that are reduced or eliminated when lying down). Inclusion criteria post SARS-CoV-2 onset ME/CFS: * 18-70 years of age * At least 8th grade education * Previous suspected, probable, or confirmed SARS-CoV-2 infection, as defined by the World Health Organization: * Suspected case of SARS-CoV-2 infection * Three options, A through C: Meets the clinical OR epidemiological criteria. * Clinical criteria: Acute onset of fever AND cough (influenza-like illness) OR Acute onset of ANY THREE OR MORE of the following signs or symptoms: fever, cough, general, weakness/fatigue, headache, myalgia, sore throat, coryza, dyspnea, nausea, diarrhea, anorexia. * Epidemiological criteria: …