Chronic Fatigue Syndrome and Long-Covid: Q&A with Dr Jenner

28 Jun 2021

Is it possible to distinguish between a patient suffering from post-traumatic Chronic Fatigue Syndrome (CFS) and a patient suffering from long Covid?

There is a considerable overlap in symptoms between these two conditions, which would make a definite diagnosis hard to establish. Furthermore, the current understanding of long COVID is limited as it is such a new phenomenon. It is possible that the two conditions form part of a spectrum of dysregulated inflammatory and immune responses by the body to viral illnesses, where long COVID is distinguishable by its known aetiology.

What are the hallmarks of each?

CFS is characterised by chronic exhaustion and fatigue, typically lasting for at least 6 months. Women are more commonly affected than men. Other major symptoms include post-exercise malaise and sleep disturbances. Less common symptoms are pain (headaches, muscular pain, joint pain), cognitive difficulties (brain fog) and muscle weakness (1,2).

There is currently no universal definition for long COVID. The three major symptoms of CFS, chronic fatigue, post-exercise malaise and reduced daily activity are also frequently reported in long COVID patients, as are the minor symptoms (1,2). The only symptoms that appear to be unique to long COVID are disturbances of taste and smell, and to a lesser extent hearing, and the presence of a rash (1).

Theoretically, if a claimant sustained a traumatic injury 12 months ago and they also returned a positive covid result around the same time, how would you address causation of subsequent CFS?

It would be very difficult to distinguish between CFS and long-COVID in this situation. The close timing of the two potentially triggering events would make it very difficult to state with any certainty whether this was a case of long COVID or CFS arising from a traumatic injury. Although medical history would obviously be important, there is no clear link between the severity of COVID symptoms and the risk of developing long COVID (1). Therefore, a patient who is relatively mildly affected by COVID could go on to develop chronic symptoms. Furthermore, a diagnosis of long COVID does not necessarily require a positive COVID test – in the early stages of the pandemic, many people did not have access to testing (3).

What features (if any) would persuade you that the patient had either post traumatic CFS or, in the alternative, long covid? To what extent is it a matter of statistical analysis?

If the patient reported taste or smell disturbances, or a rash, among their symptoms, this would indicate a diagnosis of long COVID rather than CFS. The time period over which the symptoms persisted would also be important: CFS symptoms normally persist for at least 6 months (Wong). While the situation with long COVID is less clear, most patients report that their symptoms improve within a few months, although some do persist for much longer. Statistical analysis would probably not be particularly helpful in determining the diagnosis. For one thing, the wide variation in diagnostic criteria for both conditions makes quantitative analysis extremely difficult – studies may not be comparing like with like. Therefore, the type and duration of symptoms, and case history would be far more important, and these would almost certainly need to be assessed on a case-by-case basis.

Read Dr Jenner’s full article on The Link Between Long Covid and Chronic Fatigue Syndrome here.


  1. Wong TL, Weitzer DJ. Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)-A Systemic Review and Comparison of Clinical Presentation and Symptomatology. Medicina (Kaunas). 2021;57:418.
  2. NICE guideline on Long Covid fails to acknowledge important clinical and pathological overlaps with ME/CFS | The BMJ [Internet]. [cited 2021 May 27]. Available from:
  3. Sivan M, Taylor S. NICE guideline on long covid. BMJ. 2020;371:m4938.