The long-term lethargy was reported in patients with symptoms from mild to severe.

While Covid-19 symptoms, including fever, muscle weakness, shortness of breath, vomiting and diarrhea, have been well publicized, Townsend said, "the medium- and long-term consequences of infection remain unexplored.".

The research, which will be presented at a virtual meeting of the European Society of Clinical Microbiology and Infectious Diseases, is based on 128 former Covid-19 patients.

Englund, who wasn't involved with the research, said that while fatigue can be somewhat subjective, measurable physical problems can, indeed, be identified long after the body clears the coronavirus

The study found that even people who were never sick enough to be hospitalized reported long-term fatigue

"This study highlights the importance of assessing those recovering from COVID-19 for symptoms of severe fatigue, irrespective of severity of initial illness, and may identify a group worthy of further study and early intervention," the study authors wrote