Studies have confirmed that fatigue is the most common feature of long COVID-19, and in a considerable proportion of patients, it is the most stubborn.

Among 239 people from online support groups for long COVID, 85% reported having severe fatigue when a survey was done 11 weeks after symptom onset, reported Maarten Van Herck, a PhD student at the University of Hasselt in the Netherlands, at the European Respiratory Society′s virtual annual meeting. At week 24, around 79% reported that they had severe fatigue, with 15 of the 35 individuals who reported having mild or no fatigue at week 11 now indicating that their fatigue was severe. A total of 31 out of 178 individuals reporting severe fatigue initially, stated that it had become milder or had disappeared… (Medpage Today)