Clinical characteristics of Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS) diagnosed in patients with long COVID


16.8% of long COVID patients at a Japanese outpatient centre met the ME/CFS criteria, 51.1% were female. Main symptoms were fatigue and PEM, followed by headache and insomnia. To get a fuller picture symptoms would need to be tracked over a longer period of time and housebound patients included.


Research abstract:

Background and Objectives:

COVID-19 can be serious not only in the acute phase but also after the acute phase and some patients develop ME/CFS. There have been few studies on patients with long COVID in whom ME/CFS was diagnosed by physicians based on standardized criteria after examinations and exclusion diagnosis and not based on only subjective symptoms. The purpose of this study was to elucidate the detailed characteristics of ME/CFS in patients with long COVID.

Materials and Methods:

A retrospective descriptive study was performed for patients who visited a COVID-19 aftercare clinic established in Okayama University Hospital [Japan] during the period was from February 2021 to April 2022.


Clinical data were obtained from medical records for 281 patients, and 279 patients who met the definition of long COVID were included. The overall prevalence rate of ME/CFS diagnosed by three sets of ME/CFS criteria (Fukuda, Canadian and IOM criteria) was 16.8% (48.9% in male and 51.1% in females).

The most frequent symptoms in ME/CFS patients were general fatigue and post-exertional malaise (89.4% of the patients), headache (34.0%), insomnia (23.4%), dysosmia (21.3%) and dysgeusia (19.1%). Dizziness, chest pain, insomnia and headache were characteristic symptoms related to ME/CFS.

The male to female ratio in ME/CFS patients was equal in the present study, although ME/CFS was generally more common in women in previous studies. Given that patients with ME/CFS had more severe conditions in the acute phase of COVID-19, the severity of the acute infectious state might be involved in the pathophysiology of ME/CFS.


The prevalence rate of ME/CFS and the characteristic sequelae in the long COVID condition were revealed in this study.

Authors: Kazuki Tokumasu; Hiroyuki Honda; Naruhiko Sunada; Yasue Sakurada; Yui Matsuda; Koichiro Yamamoto; Yasuhiro Nakano; Toru Hasegawa; Yukichika Yamamoto; Yuki Otsuka; Hideharu Hagiya; Hitomi Kataoka; Keigo Ueda and Fumio Otsuka

Journal: Medicina 2022, 58(7), 850; []  Published: 25 June 2022 (This article belongs to the Special Issue Advances in ME/CFS Research and Clinical Care)


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