Table 1 Inclusion and exclusion criteria

a) Diagnosed with symptomatic COVID-19, confirmed by a positive PCR for SARS-CoV-2 or another positive NAAT test (RT-PCR, LAMP, TMA or mPOCT) or positive SARS-CoV-2 serology or a positive Antigen test or CORADS 4 or 5 on CT-scan.

b) Three up to including 12 months after being diagnosed with COVID-19 or after hospital discharge in case the patient was admitted.

c) Severe fatigue, operationalised as a score of ≥ 35 on the subscale fatigue of the Checklist Individual Strength (CIS) [38]. Fatigue started with or increased substantially directly after the onset of symptoms of COVID-19, as reported by the patient and confirmed by their GP or treating physician.

d) Limitations in physical functioning operationalised as a score of ≤ 65 on the Short Form Health Survey (SF-36) [40] or social disability operationalised as a score of ≥ 10 on the Work and Social Adjustment Scale (WSAS) [41].

e) Age of 18 years or older.

f) Sufficient command of the Dutch language.

a) Known psychiatric or somatic condition that can explain the fatigue. Screening for somatic condition is done by the referring physician or the patient’s GP in case of self-referral. Participants are screened for the presence of post-traumatic stress disorder (PTSD) with the PTSD Checklist for DSM-5 (PCL-5) [42] and for the presence of depressive disorder with the Beck Depression Inventory for Primary Care (BDI-PC) [43, 44]. When the score on the BDI-PC is ≥ 4 or the score on the PCL-5 is ≥ 33, the Mini-International Neuropsychiatric Interview (M.I.N.I.) [45] is conducted to determine if patients meet the criteria of PTSD or a depressive disorder.

b) Current participation in a multi-disciplinary rehabilitation programme aimed to ameliorate the consequences of COVID-19.

c) Objective hypoxaemia in rest for which oxygen therapy at home is indicated.