Long COVID Study for Neurological Symptoms

* INCLUSION CRITERIA: Recovered Volunteers (RV): Six healthy persons who have recovered from an acute SARS-CoV-2 infection. Inclusion criteria: * Participants 18 and older * Ability to provide informed consent * Completed participation in Phase B of Protocol 000089 * Met 000089 Inclusion criteria for Mild to Moderate COVID-19 without PASC symptoms: * Licensed Independent Practitioner documentation of a stable state of general well-health and physical function prior to contracting SARS-CoV-2. This may include medical records, correspondence letters, or information gathered from telephone calls with study personnel. * A self-reported illness narrative of recovery to prior health after a SARS/CoV2 infection. * Laboratory documentation of a positive COVID-19 PCR, NAA, or other EUA Approved test to confirm active COVID infection at the time of the SARS-CoV-2 infection. Participants with positive home tests during Phase A will be required to have a positive anti-SARS nucleocapsid antibody test. * Meets WHO Clinical Progression Scale of 2 - 6: 2: Ambulatory; symptomatic, independent 3: Ambulatory; symptomatic, assistance needed 4: Hospitalized; no oxygen therapy 5: Hospitalized; oxygen by mask or nasal prongs 6: Hospitalized; oxygen by non-invasive ventilation or high flow oxygen * Functional Criteria: No substantial symptom severity as determined using SF-36v2: score of \>=85 physical function subscale, and \>=85 on role physical subscale, and \>=85 on social function subscale. * Determined to be a Healthy Comparator by the 000089 Case Adjudication Committee * Does not have an active SARS-CoV-2 infection. The protocol will conform with NIH CC standards for documenting a participant does not have active SARS-CoV-2 infection. This may include screening interviews and/or testing. Testing may be repeated with each admission. Participants may be rescreened 6 weeks after acute infection has resolved. Neurologic Post-Acute Sequelae of COVID-19 Participants (Neuro-PASC): Six persons with ongoing neurological complaints following an acute SARS-CoV-2 infection. Inclusion criteria: * Participants 18 and older * Ability to provide informed consent * Completed participation in Phase B of Protocol 000089 * Met 000089 Inclusion criteria for Mild to Moderate COVID-19 with PASC symptoms: * Licensed Independent Practitioner documentation of a stable state of general well-health and physical function prior to contracting SARS-CoV-2. This may include medical records, correspondence letters, or information gathered from telephone calls with study personnel. * 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, unrefreshing sleep, neuropathic pain, mood change, and post-exertional malaise. * Laboratory documentation of a positive COVID-19 PCR, NAA, or other EUA Approved test to confirm active COVID infection at the time of the SARS-CoV-2 infection. Participants with positive home tests during Phase A will be required to have a positive anti-SARS nucleocapsid antibody test . * Meets WHO Clinical Progression Scale of 2 - 6: 2: Ambulatory; symptomatic, independent 3: Ambulatory; symptomatic, assistance needed 4: Hospitalized; no oxygen therapy 5: Hospitalized; oxygen by mask or nasal prongs 6: Hospitalized; oxygen by non-invasive ventilation or high flow oxygen * Functional Criteria: Substantial symptom severity as determined using SF-36v2: score of \<= 70 physical function subscale, or \<=50 on role physical subscale, or \<=75 on social function subscale. * Determined to have Post-Acute Sequelae of COVID-19 by the 000089 Case Adjudication Committee * Primary PASC complaint is neurologic including: * Neuropathic sensations * Cognitive complaints * Postural (Orthostatic) complaints * Motor complaints * Does not have an active SARS-CoV-2 infection. The protocol will conform with NIH CC standards for documenting a participant does not have active SARS-CoV-2 infection. This may include screening interviews and/or testing. Testing may be repeated with each admission. Participants may be rescreened 6 weeks after acute infection has resolved. EXCLUSION CRITERIA: * Current suicidal ideation * Women who are pregnant, breastfeeding, or are within one-year post-partum. * Current or previous malignancy. A history of malignancy that has fully resolved with surgical resection only (e.g. no chemotherapy, radiation therapy, or immunotherapy) will be allowed. * Current systemic immunologic disorders (e.g. Type 1 diabetes, rheumatoid arthritis). Local immunological disorder (e.g. atopic dermatitis, stable autoimmune thyroid disease) and allergic disorders will be allowed. * Current or previous long-term immune suppressive therapy. Systemic steroid use, even short-term, must not have been used within the month prior to enrollment. * Long term use of anticoagulant or antiplatelet medications. * Active participation in a clinical protocol (e.g. anti-inflammatory drug intervention study) which includes an intervention that may affect the results of the current study. * Not willing to allow for research data and samples to be shared broadly with other researchers. * Employees of NIH. * Symptom severity that makes it impossible for the volunteer to travel to NIH for an extended inpatient evaluation * Use of medications with a high-risk for withdrawal-related complications (i.e. long-acting opiates or benzodiazepines). * Unwillingness to co-enroll in protocol 17-I-0122: NIAID Centralized Sequencing Protocol.