text: Severe Fatigue in Long COVID Web Based Quantitative Follow up Study in Members of Online Long COVID Support Groups Fatigue is the most commonly reported symptom in patients with persistent complaints following COVID 19 ie long COVID Longitudinal studies examining the intensity of fatigue and differentiating between physical and mental fatigue are lacking The objectives of this study were to 1 assess the severity of fatigue over time in members of online long COVID peer support groups and 2 assess whether members of these groups experienced mental fatigue physical fatigue or both A 2 wave web based follow up study was conducted in members of online long COVID peer support groups with a confirmed diagnosis approximately 3 and 6 months after the onset of infectious symptoms Demographics COVID 19 diagnosis received health care from medical professionals or allied health care professionals fatigue Checklist Individual Strength subscale subjective fatigue CIS Fatigue 8 56 points and physical and mental fatigue self constructed questions 3 21 points were assessed Higher scores indicated more severe fatigue A CIS Fatigue score 36 points was used to qualify patients as having severe fatigue A total of 239 patients with polymerase chain reaction computed tomography confirmed COVID 19 completed the survey 10 weeks SD 2 and 23 weeks SD 2 after onset of infectious symptoms respectively T1 and T2 Of these 239 patients 198 82 8 were women 142 59 4 had no self reported pre existing comorbidities 208 87 self reported being in good health before contracting COVID 19 and 62 25 9 were hospitalized during acute infection The median age was 50 years IQR 39 56 The vast majority of patients had severe fatigue at T1 and T2 n 204 85 4 and n 188 78 7 respectively No significant differences were found in the prevalence of normal mild and severe fatigue between T1 and T2 P 12 The median CIS Fatigue score was 48 points IQR 42 53 at T1 and it decreased from T1 to T2 median change 2 points IQR 7 to 3 P 001 At T1 a median physical fatigue score of 19 points IQR 16 20 and a median mental fatigue score of 15 points IQR 10 17 were reported these scores were lower at T2 for physical but not for mental fatigue median change for physical fatigue 1 point IQR 3 to 0 P 001 median change for mental fatigue 0 points IQR 3 to 3 P 52 At the time of completing the follow up survey 194 239 81 2 and 164 239 68 6 of all patients had received care from at least one medical professional and one allied health care professional respectively Fatigue in members of online long COVID support groups with a confirmed COVID 19 diagnosis decreases from 10 to 23 weeks after onset of symptoms Despite this severe fatigue remains highly prevalent Both physical and mental fatigue are present It remains unclear whether and to what extent fatigue will resolve spontaneously in the longer term Netherlands Trial Register NTR8705 https www trialregister nl trial 8705 