The complex clinical symptoms of post COVID syndrome, especially chronic fatigue, pose a major challenge to patients and to the health care system and are frequently refractory to therapeutic intervention. There is increasing evidence that a dysregulated post-viral immune response may be involved in the pathogenesis of post COVID syndrome. In uncontrolled case studies, an improvement of fatigue symptoms after removing autoantibodies has been reported in post COVID patients. However, there is a lack of prospective, sham controlled studies. We initiate an interventional, randomised, sham treatment-controlled prospective study, the EXTINCT post COVID study, which aims to scientifically test the therapeutic efficacy of an extracorporeal apheresis procedure (immunoadsorption) for the treatment of a well characterized cohort of patients with post COVID syndrome, while at the same time providing basic research evidence for an understanding of the pathogenesis of post COVID syndrome. Thereby, we expect to obtain important insights into the diagnosis, treatment and pathophysiology of post-COVID syndrome.

Inclusion Criteria:

1. Age 18-75 years
2. Chronic Fatigue Syndrome (CFS) according to Canadian Consensus Criteria (at two time points > 4 weeks apart) with a duration of > 6 months with new onset < 12 weeks after PCR test confirmed SARS-CoV2-infection
3. Chalder Fatigue Scale >/= 4 binary scale (at two time points > 4 weeks apart)
4. Post exertional malaise >/= 14 h (at two time points > 4 weeks apart)
5. Bell Scale 20-50 (at two time points > 4 weeks apart)
6. Willing to comply with all aspects of the protocol, including blood draws, magnetic resonance imaging and ophthalmological evaluation
7. Patient is able to understand and fully participate in the activities of the study and consent in accordance with guidelines
8. Female patients of childbearing potential who are sexually active must be willing to use an acceptable form of contraception. Female patients must not be pregnant, planning to become pregnant, or be actively breastfeeding through the entire period.

Exclusion citeria:

1. Chronic fatigue due to other medical or psychological condition
2. Preexisting chronic fatigue prior to COVID infection
3. Oxygen requirement or ventilation during acute phase of COVID
4. Positive SARS-CoV-2-PCR test at the beginning of the study
5. Comorbidity bearing risk that patient might not tolerate treatment as judged by investigator including among others: malignant disease within the last 5 years, moderate to severe renal impairment (eGFR <60 ml/min), cardiac insufficiency (LVEF <40%), severe coronary heart disease, severe hypercoagulability
6. Acute or severe psychiatric disease
7. Active/acute infectious diseases like CMV, EBV, HBV, HCV, HIV, TBC
8. Patients who in the investigator's opinion might not be suitable for study (difficult peripheral venous access, not able to complete questionnaires e.g. due to language problems)
9. Taking immunosuppressive medication >3 weeks within 12 months before study inclusion
10. Any apheresis therapy before study inclusion
11. Contraindications for magnetic resonance imaging
12. Patients revealing abnormal brain structures visible in MR images
13. Patients with pre-existing ophthalmological condition or diabetes mellitus

double-blind