Safety, Efficacy, and Dosing of VIX001 in Patients With Neurological Symptoms of Post Acute COVID-19 Syndrome (PACS).

Inclusion Criteria: 1. Age ≥ 18 years. 2. Has had prior laboratory-confirmed SARS-CoV-2 infection as determined by an approved polymerase chain reaction (PCR) or an approved antigen test of any specimen, which did not require intubation or mechanical or non-invasive ventilation to address the SARS-CoV-2 infection. Only those who had COVID-19 and who were not hospitalized for their infection and are eligible for this study. 3. Has had a recent (within a week) negative SARS-CoV-2 test (an approved PCR or antigen test). 4. Has had at least moderate or severe post-COVID-19 symptoms for at least 3 months which have resulted in reduced functioning compared to pre-COVID-19 status, and a working diagnosis of post-acute COVID-19 syndrome (PACS). 5. Ability to comply with the requirements of the study, including anticipated ability to attend all scheduled visits. 6. Ability to understand and provide written informed consent. 7. All participants of reproductive age/capacity will be required to use adequate contraception, defined as two forms of highly effective contraceptives, with any partners during the study period and for at least three months beyond the study period for safety. 8. The primary presenting symptom impeding daily function is neurological. 9. Severity of cognitive impairment/brain fog measured by MoCA score of ≤ 24 \[40\] that was not present prior to contracting COVID-19. A score of 18-26 indicates mild cognitive impairment. A score of 17 or less may indicate moderate impairment. This study will enroll patients with so-called "brain fog," or mild impairment to the degree that would not affect capacity to consent. A careful history will be taken to ensure that the symptoms of cognitive impairment found to be limiting by the patient and their family (if applicable) have developed subsequent to the COVID-19 infection, and were not present previously. If the temporal course of the clinical history is not clearly related to the acute infection, the patient will not be considered for inclusion. In parallel, the following neurological symptoms will be assessed and monitored as exploratory endpoints, but are not inclusion criteria: * Objective assessment of orthostatic intolerance as determined by a change of 30 in pulse or blood pressure on NASA 10-Minute Lean Test in patients who had no prior history of autonomic dysfunction; * Symptomatic depression (defined as a score of \<10 on the PHQ-8 patient reported outcome questionnaire) at the time of screening that must have been controlled on a stable therapy (pharmacological or in the care of a therapist) for three months prior to planned infusion, are under the active care of a mental health provider during the study period, and was not present prior to contracting COVID-19.; * Anxiety on GAD-7 with a score of ≥10 and ≤ 15 that was not present prior to contracting COVID-19; and * Sleep disturbance on PROMIS-SD with a score of ≥30 that was not present prior to contracting COVID-19. Exclusion Criteria: 1. Significant concurrent medical conditions (verified by medical records as needed), including the following: * Poorly controlled diabetes mellitus, defined as HbA1C\>8.5. * Medical History of Chronic kidney disease (CKD) diagnosis and/or screening results of eGFR \< 60mL/min/1.73m2. * Presence of New York Heart Association (NYHA) Class III/IV heart failure during screening visit. * Blood pressure \> 180/110 mm/Hg during screening visit. * Chronic obstructive pulmonary disease (COPD). * Participants with HIV, Hepatitis B and Hepatitis C. 2. Participants with a prior history of stroke, neurogenerative disease, dementia, or developmental delay. 3. Participants with \< 18 on MoCA will be excluded, as well as any who have an active power of attorney or other legal basis to be deemed to lack capacity. 4. Participants who require ongoing oxygen ventilation. 5. Other clinically significant, ongoing illness or medical condition, that in the opinion of the investigator constitutes a safety risk for participation in the study or that could interfere with achieving the study objectives, conduct or evaluation, including a history of thromboembolic events. 6. Participants who are pregnant or lactating. 7. Active alcohol or substance abuse or any other reason that makes it unlikely that the participant will comply with study procedures. 8. Infusion of any other investigational agents within 6 months of randomization. 9. All subjects with PHQ-8 score \>10 at the time of enrollment screening will be excluded from the study. 10. Participants with a psychiatric illness or condition, which, in the opinion of the investigation, would interfere with the conduct of the study or the interpretation of study results. Participants with stable anxiety and depression (PHQ-8 score of \<10) defined as being on stable doses of antidepressant and anxiety drugs for the last 3 months and for which no dose changes are expected during the study can be included. Participants who are not under the active care of a mental health provider during the study period will be excluded. 11. Participants with autoimmune disease or a known history of having Acquired Immunodeficiency Syndromes (AIDS) or Human Immunodeficiency Virus (HIV). 12. Participant has known alcoholic addiction or dependency, uses alcohol daily, or has current substance use or abuse. 13. Participant has any active malignancy, including evidence of cutaneous basal, squamous cell carcinoma, or melanoma. 14. Participant was either diagnosed with or reasonably believed to have had Chronic Fatigue Syndrome, Sleep Apnea, Insomnia, or any other sleep disorder prior to contracting COVID-19. 15. Significant laboratory abnormalities, including any of the following * White blood cell count \< 3000/mm3. * Platelet count \< 125,000 mm3. * Absolute neutrophil count \< 1500/mm3. * Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \> upper limit of normal (ULN) x 1.5. * any other laboratory abnormality, which, in the opinion of the investigator poses a safety risk or will prevent the participant for completing the study. * Uncontrolled Hyperthyroidism or Hypothyroidism or any other Thyroid disease reflected by abnormal TSH per local laboratory. Those with abnormal TSH in conjunction with either an abnormal T3 or Free T4 will be excluded. 16. Recent vaccination against SARS-CoV-2 within the last 30 days.