Severe Fatigue in Long COVID: Web-Based Quantitative Follow-up Study in Members of Online Long COVID Support Groups

Maarten Van Herck   ^{1, 2, 3, 4 *} , MSc ;   Yvonne M J Goërtz   ^{2, 3, 4 *} , MSc ;   Sarah Houben-Wilke   ² , PhD ;   Felipe V C Machado   ^{2, 3, 4} , MSc ;   Roy Meys   ^{2, 3, 4} , MSc ;   Jeannet M Delbressine   ² , MSc ;   Anouk W Vaes   ² , PhD ;   Chris Burtin   ¹ , PhD ;   Rein Posthuma   ^{2, 3, 4} , MD ;   Frits M E Franssen   ^{2, 3, 4} , MD, PhD ;   Bita Hajian   ² , MD, PhD ;   Herman Vijlbrief   ⁵ , MSc ;   Yvonne Spies   ⁵ , MSc ;   Alex J van 't Hul   ⁶ , PhD ;   Daisy J A Janssen   ^{2, 7} , MD, PhD ;   Martijn A Spruit   ^{2, 3, 4} , Prof Dr

¹ REVAL Rehabilitation Research Center, BIOMED Research Institute, Faculty of Rehabilitation Sciences, Hasselt University, Diepenbeek, Belgium

² Department of Research and Development, Ciro, Horn, Netherlands, The

³ Nutrim School of Nutrition and Translational Research in Metabolism, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Netherlands, The

⁴ Department of Respiratory Medicine, Maastricht University Medical Centre, Maastricht, Netherlands, The

⁵ Lung Foundation Netherlands, Amersfoort, Netherlands, The

⁶ Department of Pulmonary Disease, Radboud University Medical Center, Nijmegen, Netherlands, The

⁷ Department of Health Services Research, Care and Public Health Research Institute, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Netherlands, The

*these authors contributed equally