The condition is poorly understood, but there is evidence that people can develop CFS /ME following a viral infection – such as viral meningitis or Epstein-Barr virus, which causes glandular fever.
A study led by Dr Moldofsky following the Sars outbreak in Canada in 2002 to 2003 also found that some patients continued to have symptoms similar to CFS/ME for years after they were diagnosed with the coronavirus, which is closely related to Sars-Cov-2.
The research, published in 2011, concluded that “chronic post-Sars is characterised by persistent fatigue, diffuse myalgia, weakness, depression, and nonrestorative sleep”.
The paper studied 22 post-Sars patients with ongoing health problems that prevented them from returning to work, though these people represent only about eight per cent of the 273 people diagnosed with Sars in Toronto.
But another study published in the Journal of the American Medical Association in 2009 found that 40 per cent of 369 Sars survivors studied in China reported a “chronic fatigue problem”, while 27 per cent met the US Centers for Disease Control and Prevention definition for CFS/ME.
However Paul Hunter, professor in medicine at the University of East Anglia, said that the proportion of Covid-19 patients with chronic fatigue may be lower because Sars “tended to be a more severe illness”.