IMAGE DESCRIPTION: An image of a real person with ME/CFS with an image of the Covid virus (top right) Wording: The title of the blog and the ME Association logo (bottom right)

Research: ME/CFS is Common in Long Covid

ME Association Comment

“I’m sure that this will be the first of many research studies to confirm that infection with Covid-19 can cause persisting ill health (i.e., Long Covid) that often involves ME/CFS-type symptoms and in some cases an illness that is identical to ME/CFS (43% in this research study).

“Please note that this research is still in a pre-print form. Before formal publication in a scholarly journal, scientific and medical articles are traditionally certified by “peer review.” In this process, the journal’s editors take advice from various experts – called “referees” – who have assessed the paper and may identify weaknesses in its assumptions, methods, and conclusions.”

Dr Charles Shepherd

The Research


The global prevalence of PASC is estimated to be present in 0.43 and based on the WHO estimation of 470 million worldwide COVID-19 infections, corresponds to around 200 million people experiencing long COVID symptoms. Despite this, its clinical features are not well defined.


We collected retrospective data from 140 patients with PASC in a post-COVID-19 clinic on demographics, risk factors, illness severity (graded as one-mild to five-severe), functional status, and 29 symptoms and principal component symptoms cluster analysis. The Institute of Medicine (IOM) 2015 criteria were used to determine the ME/CFS phenotype.


The median age was 47 years, 59.0% were female; 49.3% White, 17.2% Hispanic, 14.9% Asian, and 6.7% Black. Only 12.7% required hospitalization. Seventy-two (53.5%) patients had no known comorbid conditions. Forty-five (33.9%) were significantly debilitated. The median duration of symptoms was 285.5 days, and the number of symptoms was 12. The most common symptoms were fatigue (86.5%), post-exertional malaise (82.8%), brain fog (81.2%), unrefreshing sleep (76.7%), and lethargy (74.6%). Forty-three percent fit the criteria for ME/CFS.


Most PASC patients evaluated at our clinic had no comorbid condition and were not hospitalized for acute COVID-19. One-third of patients experienced a severe decline in their functional status. About 43% had the ME/CFS subtype.

Dr Charles Shepherd,
Trustee and
Hon. Medical Adviser
to the ME Association.
Member of the 2018-2021 NICE Guideline Committee.
Member of the 2002 Independent Working Group on ME/CFS.

Dr Charles Shepherd
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