Could an immune treatment ease long COVID brain fog?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

* INCLUSION CRITERIA: In order to be eligible to participate in this study, an individual must meet all of the following criteria: * Stated willingness to comply with all study procedures and availability for the duration of the study. * Male or female, aged at least 18 and older. * Meets the inclusion/exclusion criteria and is enrolled in Phase A of Protocol 000089 "Post-Coronavirus Disease 19 Convalescence at the National Institutes of Health." * Previously diagnosed with mild-moderate COVID-19 (WHO Clinical Progression Scale between 2-5. Patients with severe acute COVID-19 requiring hospitalization or ICU care are excluded. Enrollment could take place 12 weeks after the diagnosis of acute COVID-19. * Prior COVID-19 diagnosis confirmed by patient reported infection followed by confirmatory nucleocapsid antibody testing or a positive SARS-CoV-2 PCR test result from the time of infection. * Exhibiting persistent neurologic symptoms evidenced by a self-reported illness narrative of the development of persistent PASC symptoms after recovering from a SARS-CoV-2 infection. These include symptoms such as fatigue, cognitive difficulties, orthostatic intolerance, and any ongoing issues with gait instability, vision, speech, swallowing, sensation or strength. * Non-negligible PASC symptom severity, as determined using PCFS (minimal score of 2). * Ability of subject to understand and the willingness to sign a written informed consent document. * Prior completion of a clinical brain MRI after the diagnosis of COVID-19, or willingness to complete a brain MRI. * Meets current Clinical Center HES' policy for discontinuing isolation and quarantine for COVID-19. EXCLUSION CRITERIA: An individual who meets any of the following criteria will be excluded from participation in this study: \- For participants who have not completed a brain MRI since onset of symptoms: inability to complete brain MRI with gadolinium including contraindicated metal in the body, prior allergic reaction to gadolinium, eGFR \<45 mmol/L, pregnancy or lactation, or claustrophobia that is unable to be adequately treated with a low dose oral benzodiazepine. * Contraindication to a research lumbar puncture, including use of anticoagulant medication, platelets \< 50,000/uL, PT or PTT \>1.5 x ULN for the NIH Clinical Center, or otherwise inability to complete the procedure. * A condition that would significantly confound interpretation of the clinical and research tests as determined by the study investigators. This could include: traumatic brain injury, substance use disorder, active malignancy, systemic immunologic disorders, current or previous long-term immune suppressive therapy. * Received a SARS-CoV-2 vaccine dose within less than 4 weeks of enrollment or is planning for any additional vaccines during the course of the study. * Prior experimental treatment for PASC with immunoglobulins. * Current medications include oral steroids or other immunosuppressive medications. * Active participation in a clinical protocol which includes any intervention that may affect the results of the current study. * Contraindication of intravenous immunoglobulins, including: * Renal insufficiency (eGFR\<45mmol/L) * IgA deficiency * History of ischemic heart disease * Peripheral vascular disease * Cerebrovascular disease * Previously diagnosed hypercoagulability syndrome including antiphospholipid antibody syndrome, Protein C/S deficiency, Factor V Leiden, Antithrombin deficiency, MTHFR homozygosity * Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than 3.0 times the upper limit of normal.precluding the use of acetaminophen. * Previously documented anaphylaxis or severe systemic reaction to immunoglobulins, acetaminophen, or diphenhydramine. * A severe psychiatric condition, which based on the assessment of the study investigators, will impact the ability to complete the 12-week study course.